Be fair, be wise. Be a friend with him. You two can still be the parents for your son.
It's not going to be easy. But time can fade awy everything. For the son, he will understand, especially when he grow older and understand more about homosexuality.
If you love somebody strong enough, you can do any sacrafice.
life is too short and do something happy. Sometimes things just happen you cann't explain. He needs the guts to be the person he wants to be. He is still struglling because he is not getting there.