I'm so sorry you are going thru this. Has your son gone to counseling? If not, you really should try to get him to see a counselor who has experience with victims of child sexual abuse. If he's been thru counseling, it may be that he really just needs to see that you are not focusing on it alot and needs you to be interested in and supportive of other activities and interests he has. It would be really great if a trusted adult male friend or family member (or two) could be there occasionally for him to fill in for what he's missing with his dad being out of the picture. But he also needs to see that this issue isn't a silent undercurrent (or the big white elephant in the room) in everyday routines and happenings. He and you need to do things as normally as possible so that it will begin to feel that way, and grow in that normal feeling. Things will never be back to the same as they were, but they can come fairly close with practice. He should understand that every now and then he needs to be open to you checking in and having a bit of honest dialogue so you can keep on top of how you each are doing.
Not all victims have a really hard time with what happened to them. Many become very determined to rise above it and be successful. My son had a delayed response and delayed disclosure--he used his musical talent to excel at things in that area as a way of coping and overcoming, despite the fact that his offender was one of his instructors. He didn't disclose to us until 3 yrs after the abuse started; he stopped it after about 11 mos, but didn't tell us until he was leaving for college and became too overwhelmed and panicky. We had to let him go 3 hrs away, got him into counseling, went to see him alot, and let him figure out how he wanted to handle everything. We did alot of research for him, had open communication with him about everything but not too frequently, and let him make the decisions about what he wanted to do, when he wanted to do it, and how he wanted us to support him. But he was an adult, and we had no choice but to do it that way. It did take us a while to get him to agree to try counseling, and after the first session, he saw that it wasn;t what he thought it would be and did actually like it. However, he has always remained dedicated to his instrument and became very proficient--he has several scholarships and is at the top of his ensembles. He does still struggle with flashbacks and feelings of self loathing at times, but it's improving and he's still going to counseling.
If there are gifts or talents your son has, you could guide him into participation in those activities and support him in that with praise and affirmation. Even if you are crying and falling apart out of his sight (my time for losing it is in the shower), seeing that you are embracing his interests and moving on will help him immensely. But if you are struggling, take care of you and get counseling for yourself as well from someone with sex abuse experience. It really helps. Hope this lengthy info is helpful. Don't let yourself sink too far. Be strong and proactive--take the power and control back from the offender in your situation. It's not easy but it's worth it! You're in my thoughts and prayers. (((hugs)))