Extreme regret over horrible thing I did at 14

When I was 14-15 I sexually abused my sister who was 7-8. This abuse included touching private parts and dry-humping. Altough at that age my sister was not morally able to give consent, she did not oppose this actions either. I am now almost 18 and as the years passed I began to realize how disgusting this actions were. Over the years i have also become a big feminist and researched sexual abuse and its consequences for victims and it kills me to think that my sister may one day go trough that stuff. A while ago I tried to talk with my sister about it and to explain to her that what we did was very wrong and to apologize, she did not seem bothered but I dont think she understands it yet.
I am afraid that one the day the truth of what we did will get out, but that's my smallest concern. My main concerns are: how can I live knowing that I may have seriously hurt my sister and can I ever be forgiven for what I did?
It would really help if someone has any advise.

When i was 14-15 i sexually abused my sister who was 7-8 at the time. It happened 2-3 times over the span of a week. It included touching private parts and dry-humping, and altough at that age she was not morally able to consent, she did not object to what we were doing. I suffered a lot of bullying when i was younger and was exposed to porn at a young age and maybe that contributed to this sexual problems that i had (im not trying to make excuses, this was just something i heard was possible but i have no confirmation that it may be related to it). I am now almost 18 and i am feeling miserable thinking about what i did and i cannot let it go. Over the years i became a big feminist which led me to do research on sexual abuse and its consequences on victims and it kills me to think that i may have sentenced my own sister to those things. I talked to her about it some time ago to explain that what we did was very wrong and to apologize to her, but she seemed to not want to talk about it and i think she doesnt understand the gravity of it yet. I need help. How can i live knowing that i was exactly what i now hate and despise (a sexual abuser)?. Im also afraid that she tells someone what we did , but most of all im afraid she will be forever hurt by what i did to her. I never looked at any other child that way, neither did i look at her that way.We still have a great relationship and love each other very much (in a brotherly way) I cannot explain why i did what i did that week and thats awful. I hope anyone here can help me, please.

I will admit this is a tricky situation since there is a notable age difference between yourself and your sister. I do think, however, it is important to remember that your brain (and moral development) are still very much in flux until one's early to mid 20s. As such, in a very real sense you are a different person now to who you were. Maybe you can see turning 18 as a line in the sand, leaving the actions of your child self in your childhood, while being mindful that if your sister ever feels differently about your behaviour, you should take whatever accountability she asks of you. The main thing is to put her needs first and to not insist upon her feeling weird or upset about what you did if she doesn't feel that way.

I'm going to tell you the simple truth that we all take for granted.

Humans need training. If they don't get training, by the time they hit puberty they are overcome with an instinctual drive that they don't understand.

The feeling doesn't go away and seeking information is taboo, and the information you do get about it is inadequate. You still don't get it even after it's explained. This thing feels extremely good because it is evolutionarily favorable. It keeps coming back and you don't know how settle it and move on.

It's everywhere and really never goes away. Everything is sexualized on tv and adverts. Virgin is used as an insult. It's the subject of teasing and bullying. You cannot ignore it.

After a while you try it out. You have no idea you are hurting someone. You are just trying to chase after this thing that won't go away, that nobody will explain to you in a satisfactory way.

Society is fake and produces naive children who don't understand anything, then it punishes them. It's someone's responsibility to have taught you, and those are the people who failed.

As long as you never do it again, it is clearly not your nature and was an experiment. This is probably extremely common because everyone gets this feeling and adults neglect to address it, leaving you with curiosity and this euphoric thing that won't go away.

Society isn't even consistent about this. Lena Dunham did it and it was ignored because she holds the right political opinions. Josh Duggar did it and was vilified.

The main goal should be for your sister to recover. The adults failed you hard. If you disagree with me, then answer me this: why do we have education at all? Without education we are animals or cavemen, and sex is no exception. The teachers are responsible for this.

I bet in the distant future society will have advanced enough to realize the brutality of this period in history. It sets you up to fail and then blames you for it. There's very little done for prevention, or forgiveness, or rehabilitation. We talk about those things all the time but we're full of $#%^ and never pursue those edifying remedies.

edit: one last thing.

You wronged 1 person. Others have no right to judge you. Our society has become like a tabloid and we take it for granted. But remember that you did not wrong them.