I know you posted this some time back and I hope that you are still here reading.
I am a retired psychological counselor, and I would like to see you get some counseling. There are many counselors available, and many good books as well. YOU did NOT hurt your mother by telling what was going on. HE HURT YOUR MOTHER by raping her son...she is much better off with him ot of her life. Iam sure she was stunned and also felt guilty that she didn't know and wasn't able to stop it.
You are not responsible for her happiness, though I know you want her happy...but a man like that is not going to make her happy. My heart goes out to you, and I do understand, I was also the victim of rape, by my own father over a period of many months when I was a young teenager.
You will come to acceptance of what happened, and you will know that HE is responsible foro your mother's unhappiness and your unhappiness. There's a lesson in this for you though, and that is that YOU are not responsible for hurting her. HE is.
I hope in the future if bad things are done to you that you will love and trust your mom to tell her what is going on There is no NO reason to suffer abuse of any kind, that's what mom's are for, to protect our children, so tell your mom...don't be worried abot her being upset about it....your mom is a loving woman, soo trust her. And God bless you and her. The pain will pass, you wont forget the rapes but you WILL get through this. If the kids at school give you a hard time, change schools if possible. Bullying is a no no in schools now, so talk to your school counselor he or she can help keep that sort of thing down. And, realize tooo that those bullies are NOT your friends...they are evil little troll that get their jollies hurting others. That kind of person is not worth the nail on your little finger, so just blow them off and ignore them. Again, God bless you.