First, let me say I am sorry to hear what was perpatrated upon your son. Second, I myself am a suvivor of clergy abuse. From the time I was 12 for several years I was sexually, physically and emotionally abused by a priest. I tried to speak up but the local bishop covered everything up. But that is a entirely different story which I may share at another time.
It is not at all uncommon for any male child/adolescent to question his sexual orientation after such victimization (even males who were not abused may also deal with this question). I did myself for many years. I would think that at his age his sexual drive is in overdrive...his body responded to these advances as any male body would. He probably experienced physical pleasure but the emotional/mental part is virtual torture. He is probably also experiencing shame, guilt..somehow believing it was his fault, that he could have stopped it somehow....THIS IS NOT THE CASE!
I cannot begin to speculate on what his sexual orientation may be...he will sort this out in time but it is probably a very good idea that he explore these issues with a therapist. What I think is the most important thing you can do for him right now is be careful not to add to his confusion, by setting expectations that he must be one way or the other.
What I mean is that it is probably very important for him to know that you will love him no matter what his orientation may be. What if he is attracted to other men more than woman? I can tell you that many, many men at some point in thier adolescence experience this confusion and at times express or feel attracted to other men. This does not mean that they are gay. But again I will ask...so what if he is? He is very young, this type of relationship (male/male) due to his victimization may be his only point of reference in his life. Because his body responded positively, he might think this makes him gay...it doesn't.
I am not gay and am happily married with children but I can say that for many years I was confused by this issue. He will be okay but the most important thing is that he has family who will love and support him no matter what...he didn't ask for any of this (nor did you). Your entire family was a victim of this mans seduction, manipulation and deciet. If he isn't yet, I do hope he will seek professional help, but he must want to do this...I know all to well the damage this victimization can cause. But most importantly, which I have said already and will say again...."it is most important that his family is very supportive and doesn't make him feel that he must be something other than what he is. I hope this makes sense and I hope it helps.
I hope you and your son find justice in your upcoming cases against these predators.
If you have other questions regarding clergy abuse, please feel free to post or you can e-mail me at...firstname.lastname@example.org