Sexually Aggressive child.

I need some help on this one and any advice that I can get. I have a 14 year old son who has touched other children that are younger than he is. I am a single mother and rasing both my children on my own with some help from my mom while I am at work. I found out when he was 12 that he touched my cousins little girl I put him into therapy. Then just last year he touched my best friends little girl. And just today I have learned that he has had oral sex with my younger nephew. And yes I found out that he touched my daughter and I went crazy. This is very hard for me. I have talked to my mom about this I told her that I wanted him out of my house. But it is very hard because he is my son. I am not sure as to what to do about all of this. He told me that he thought that he was bi-sexual. I don't care about that I just want him to stop doing what he is doing. I have researched on the net and I am going to talk to his dr.(therapist) first thing monday morning. But if there is any advice from anyone please give it.

JC