WTBH, ((((hugs))))
I'm so sorry this happened. I think you have been given some great advice. In particular talk to your lawyer and let her/him take the lead, file charges if possible, always bring someone with you for drop offs and pick ups.
I remember something my son in law said to me about my wife which really opened my eyes. Why are you surprised when a crazy person acts like a crazy person?
Edit: Anytime you are going to be around him assume that something like this is going to happen. Self defense courses teach something called awareness/threat levels. When you are going to be around him treat it as a high danger situation or a red alert. Also you could insist, through your lawyer, that all hand offs be inside a public building rather than in the parking lot or better yet supervised by an appropriate agency.
Your friend,