I can't say with any authority that therapy can't help, but instinctively I thought, "divorce the bastard" when I read this:
Quote:He has physically abused my son...
I'm a father and I cannot imagine the mindset of someone who would abuse their child, (or anyone else's child). It seems that you'd need a very severe personality defect to be able to do something that horrible.
Even IF therapy can help, do you want to risk your son, (and most likely the rest of your family), by being around him while he's getting better?