Help?

So, about a few months ago if my memory serves me correct, something somewhat traumatic happened to me.
I was play-fighting (A regular activity me and my brother used to take part in) with our mother's boyfriend at the time in my bedroom (it was just me however), when all of a sudden I bit him so that he would let go of me, which used to be a tactic I used to escape his grasp.
After I did that, we were still play-fighting, he then proceded to grab my breasts pretty hard to the point where it hurt after I bit him, which made me extremely uncomfortable, but I did not say anything as I was somewhat scared of him, and I still pretty much am to this day due to other things he did to me before which has now been resolved.
The most traumatic part of it however, is that he rubbed his thumb across my genitalia (I was wearing underwear, thank the Lord) for a second or so, and that was mainly the thing that has affected me the most.
After we both ended the play-fighting session, I crawled into bed, and cried, if I remember correctly.
A few days or so later, we were play-fighting again (again, if I remember correctly. I do not have the best memory) and again, I bit him and he grabbed my breasts and squeezed to the point where it hurt again.
All I can say now is that I'm thankful my mother has finally broken up with him, and I no longer live in fear, but these experiences still burn in my mind.
I have not been able to tell anyone about this, not even a therapist, or my own lover. I get extremely panicky whenever I think about this, and I've kept this bottled up for so long.
On a somewhat unrelated topic to the above subject (it still relates to 'sexual abuse', but more so along the lines of pervishness.)
Whenever I was in the bath, and he came into the bathroom, I always tried to cover myself up. On more than one occasion, he was the one to make sure I got out of the bath on time. I would yell at him to get out, and he would reply something along the lines of 'What? I've seen it all before!' or something equally perverted.
I'm terrified to tell this to anyone, so this is really taking quite a lot of courage to type this out. I'm hoping to tell my lover about this subject, so hopefully she can help me through the mental trauma that still lingers.

First of all, I'm sorry that you had to go through that. I know that saying sorry is like placing a band-aid on a cut that needs stitches but my band-aid has cartoon hearts filled with love and sincerity on it.

I don't know if this'll help, but I hope that you do get the courage to tell someone, because it might give me the courage to tell, too. I have a really minor case and I kind of want to seek help because it's been consuming me lately, but I'm too young to be able to do it without my parents knowing and like you - actually not really like you since everyone has different experiences and you had it worse than I did and well you get the point - the thought of telling anyone terrifies me. I hope you tell because the knowledge that someone out there was brave enough to gives me faith that things can and do get better.

But mostly, do it for yourself.
You've been through a lot, and the memories haunt you and you alone
But just know, you don't have to keep suffering on your own.
Hey that rhymed haha

Take it from a teenager with no concept of self-worth:
You are loved
You deserve said love
You deserve peace of mind
You deserve freedom

People will believe you, people won't blame you, and people will love you no matter what.

Good luck

What do you call a shirt made of corn?
A crop top HAHAHA
- not mine but it's still my favorite