hi Swift, his behaviour towards the children is appalling and dangerous. The challenge that faces you is proving it to a court. Your mother was witness to one incident, but he'll say that you simply made the rest up.
It's essential you keep a journal and other records, (credit card statements for alcohol or sex services would be good). You have medical records about the chlamydia. Write down everything you can remember about the incidents like dates and details. But number 1 step is see a lawyer and take his/her advice.
It's wise not to reveal too much to him in the meanwhile. The way he's going, hopefully he'll be his own worst enemy.