Not sure if this is in the right place but I couldn't find anything else...

Xdh and I separated 5 years ago and divorced 4 years ago.
I have sole custody of our 6yr old DS, Xdh gets fortnightly visits Friday afternoon to Sunday afternoon.
He was abusive when we were married (in all forms) and he has ALWAYS tried power games and intimidation methods but this time he is going overboard...
He has called Child Protective Services on me at least 3 times and each time they have to investigate and it's incredibly stressful even though I am not a bad parent because I have these stories you hear about kids being taken from the good parent and given to the bad parent...
My DS gets hysterical when he has to go to his dads, to the point of nearly vomiting... I know there is something going on but DS won't talk to me...
I have him on a waiting list to see a child counsellor and I'm looking for legal help.

I guess I am looking for advice on how to deal with this situation and if any one has been through this sort of thing? It's killing me that DS is going through this and the stress is causing me major anxiety...