I'm glad to hear that mediation went well. This not only signals that a good end to your saga is in sight, it's also validation that your concerns, worries and anxieties about ex were justified - if an external observer sees the same problems you did, then it's clear that you were not overreacting or behaving inappropriately. That's a nice confidence boost.
Concerning ex's dad - parents can be irrational when it comes to their children. If I had an adult son who had a restraining order against him for domestic violence I would ... ensure that he understood very very clearly that he must never raise a hand against a partner or a child ever again. Or else. But I can imagine that for many parents, they see their adult child in this screwed-up situation and they're looking for someone to blame. It can be too risky to blame the child, because that means confronting the fact that their baby is not a good person, so the only other person they can blame is you, even when it is entirely illogical to blame you.
I agree with Lexie, if you are going to be facing a lawyer in the next go-round, it would be wise to have your own lawyer.