My son doesn't want to testify

Hey guys. Its been a while. And things have been... Idek. My posts were me talking about how my 16 year old son finally told the truth about his dad's girlfriends 23 year old sexually abusing him. I started to notice he had changed before he told me. He started wetting the bed. He got random panic attacks, when my ex's girlfriend called saying her son wanted to hang out with him ny son started panicking. The girlfriends son has been arrested and my sons father stopped talking to our son because he "brought drama to their home." Seriously fuck him. My son has had a hard time. I didn't make him go to school and ended up just switching him to online for the rest of the year. His friends really missed him so they've been coming by the house to check up on him. He is doing better. Has started hanging out with friends again and smiling again. Now here's the situation. My ex's gf son originally admitted to doing it so we thought that was weight lifted off our shoulder. From my understanding of whats happening he's trying to retract his statement and plead not guilty. I didn't even know you could do that. It's looking like my son is gonna have to testify against him and when we had that talk he started panicking and crying and saying he can't do it. He doesn't want to have to sit in front of people and testify and it's causing him a lot of stress. I'm really stuck on what the right thing to do is as a mother. Tell him he doesn't have to, but leave a chance of that creep getting out. Or try to convince him to, and cause him even more distress. I really don't know what is the right thing to do. I feel like we kind of forget there would be a trial because we spent so much time trying to get him mentally healthy. Now he's starting to isolate himself again and it seems no matter what I do I'm making the wrong choice. Sometimes I think his father was right to tell me I'm a bad mother because I failed to protect him. If I could have protected him we wouldn't be in this situation and now it seems no matter what choice we make the outcome will hurt him... I feel like I can't talk to anyone else about this because it's my son's business which is why I'm happy I have you lady's. I just want to be there and protect him since I couldn't before, but I'm just failing so fucking hard and it's killing me .....