I have multiple issues going on. I've never told anyone but when I was around nine my older sister and I would kiss and play with each others genitals. I hadn't hit puberty, so I honestly didn't really know what was going on, but at the same time I knew what we were doing was wrong. Not a day goes by that I don't feel guilty, and I've never talked to anyone about it. I just keep thinking why would this happen?
I became extremely perverted after what had happened and had sexual dreams about my sister and other family members. I became so sick that I wanted some of the power I lost to my older sister back, so I started only hanging out with people that I knew I could control. When I was a freshman in High School I forced this girl with big breasts to send me pictures of her boobs, and my mom walked in on me masturbating. I've never told anyone about my mom walking in and me, and we have never talked about it; yet, every day I am bothered by it. Every day for the last five years I've replayed it in my head over and over again and again. I have begged this girl to forgive me and part of the reasons she doesn't believe in God is because of the evil I put her through. I made her send me pictures for four years. I treated her as if she was worth nothing.
Then another issue I face is that my mom walked in on me sleeping in my boxers one time and when she was leaving the room I woke up and realized I had an erection and it was hanging out of my boxers. I'm so embarrassed.
I've been holding all these secrets back and my life is affected every single day by them. My whole life has been such a perverted secret, I don't even know who I am. I feel like I have more Satan in me than Jesus. I wish every day I could go back and change these situations. I just keep hoping that the Lord will save me. I need help. I have reached out to God and it's still not helping me forgive myself and forget. I'm a disgusting monster.
I also was wondering how to get rid of the guilt of when I had just hit puberty I humped a cat and imagined it being a girl. I wish I would have been able to comprehend more and know the Lord's Word when all this horrible stuff happened.
I keep thinking: Why would God create us in such a vulnerable state (the state of childhood)? Why couldn't I just be born knowing that all this stuff was so very, very wrong? I don't know why it had to happen especially the one sin I committed when my mom saw my naked erection while I was sleeping. Why did I deserve that to happen?
This is another case where I wish you and I could sit down together and have a long talk. Not of me lecturing you, but for you to be able to talk about all the things that are bothering you, so together we can find solutions. But let's see what we can accomplish with the written word.
What your sister did with you is known as sexual abuse. More often than not when a child sexually abuses another child, it is due to the fact that the older child was also sexually abused, though not necessarily in the same way. This doesn't excuse what your sister did to you, but you do need to know that there is probably more to this sad story than you are aware of taking place.
When a child is exposed to sexual acts before reaching adolescence, what is taking place is not fully understood -- not until the child is older. Then a dilemma takes place. The child remembers that the acts felt good while knowing vaguely that it was somehow wrong. Yet there was an older person telling the child that it was all right, but it had to be kept a secret. Looking back the older child realizes that it was sexual, worse that it involved perverted sexual acts. The older child is filled with guilt over something that cannot be changed and in his memories was a willing act. The child is convinced that he is the worse person that ever lived. And the result is the sexually abused child then acts out. Exactly how varies with each person, but the motivation is common.
Even though you willingly participated in your abuse and found it physically enjoyable at the time, it does not mean you were guilty of sin. You had not yet reached an age to distinguish between good and evil. You depended on older people to tell you what was right and wrong, and your sister misled you. In this case, the burden of guilt falls squarely on your sister. "But whoever causes one of these little ones who believe in Me to sin, it would be better for him if a millstone were hung around his neck, and he were drowned in the depth of the sea. Woe to the world because of offenses! For offenses must come, but woe to that man by whom the offense comes!" (Matthew 18:6-7).
However, when you got older, you allowed the guilt of what had happened eat at you spiritual and you acted out by sexually abusing another girl for your own pleasure. You wanted control and power over the sexual part of your life that you imagined you lost to your sister. But what you did imitated what your sister did to you. You perpetuated the sin instead of taking real control and ending it. You made a girl produce pornography for you. "For this is the will of God, your sanctification: that you should abstain from sexual immorality; that each of you should know how to possess his own vessel in sanctification and honor, not in passion of lust, like the Gentiles who do not know God" (I Thessalonians 4:3-5). You didn't mention if it went further than pornography, so I'm assuming managed to stay out of fornication.
The incident of humping the cat probably arose from the same confused view of the world. It was something you could control, but you were too wrapped up in your own feelings to realize how wrong it was. Biblically the sin is called bestiality.
Now both of these sins are forgivable by God. It only requires you to submit to God's laws. I don't know your past, so see: How to Become a Christian. Even after becoming a Christian, sins can be forgiven. That is what Christianity is about. Listen to what Paul told the Corinthians, "Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God. And such were some of you. But you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus and by the Spirit of our God" (I Corinthians 6:9-11). If we leave our past sins behind, having repented of them, asking God's forgiveness (assuming that you have already become a Christian through baptism -- Galatians 3:26-29), then we forget about them and press on to the goal.
"Yes most certainly, and I count all things to be loss for the excellency of the knowledge of Christ Jesus, my Lord, for whom I suffered the loss of all things, and count them nothing but refuse, that I may gain Christ and be found in him, not having a righteousness of my own, that which is of the law, but that which is through faith in Christ, the righteousness which is from God by faith; that I may know him, and the power of his resurrection, and the fellowship of his sufferings, becoming conformed to his death; if by any means I may attain to the resurrection from the dead. Not that I have already obtained, or am already made perfect; but I press on, if it is so that I may take hold of that for which also I was taken hold of by Christ Jesus. Brothers, I don't regard myself as yet having taken hold, but one thing I do. Forgetting the things which are behind, and stretching forward to the things which are before, I press on toward the goal for the prize of the high calling of God in Christ Jesus" (Philippians 3:8-14).
Guilt is an appropriate response to realizing you have sinned. But that guilt needs to spur you to change, so that you can realize you are no longer the person you used to be.
Now, what about your mom walking in on you while you were asleep with your penis hanging out? I grant that it was extremely embarrassing, but no sin took place. Lots of guys sleep in boxers. Some sleep in the nude. Neither are wrong because you were in the privacy of your own room and, I assume, had your door closed. Having an erection is normal for guys when they sleep. Most guys get three to five erections every night, which is one reason many guys find wearing loose clothing more comfortable. Likely your mom was just as embarrassed at seeing you as you were at being seen. It is probably the reason she never mentioned it. It is also probably the reason it hasn't been repeated.
Why do we go through childhood in the manner that we do? Think about it. A small child has no impulse control. For a small boy to be able to have sex would be devastating in controlling the spread of sin. Thus, the strong desire for sex is reserved for when a boy gets older and has already learned some self-control. Yet, it comes early enough that the boy is still under his parents' authority. It is a parent's duty to protect her child from sins. That is why your mother had all those annoying rules. But even a good parent has trouble being everywhere and preventing all sin. And some parents just don't know how to handle sexual issues. For example, when your mother caught you masturbating to pornography, she should have lectured you on the dangers of pornography or had your dad talk to you instead of walking off and not saying anything. Since she didn't, I would like you to read: Lies Pornography Tells Men.
Yes, you had a bad start in the realm of sexual experiences, but it doesn't mean you are hopeless or horrible. You aren't a monster, you are young man who got off the way of righteousness. It is time to let go of sin and become a godly man. If I can help along the way, you know how to reach me.