Lost, just wanted to check in with you and see how this was going. Have you gone to the lawyer's yet?
Also, and not trying to butt in but just my two cents worth...I don't know how old your youngest is but if S2BX keeps this type of thing up, I think I would figure a way to let difficult child 2 know what's going on. Not bad mouthing an ex who's just being a jerk is one thing; the kids will figure it out on their own soon enough. But if S2BX is getting to the point that he's dangerous, (again, just me here) I think BOTH kids would need to know what's going on for safety sake if nothing else. Obviously it would need to be explained in an age appropriate manner and you could still throw some positives in...Daddy loves you but as long as he continues to make bad and possibly hurtful/dangerous choices, we have to stay away from him.
Again, not trying to offend, just MHO.
Sending {{{{HUGS}}}} to you and the kiddos.