Ex keeps bad company. I'm worried for children

We’ve been separated for 7 months. Agreement is drawn up but has yet to be signed. STBX wife has a very close ‘freind’ she exposes our young children to on a regular basis. Said friend has had a restraining order placed on him for mis-treatment of his own daughter. Just a few days ago, he was arrested for felony possesion of cocaine.

It goes without saying that I’d rather not have my children exposed to this person. What (legal) steps should I take to make sure that this man can’t bring harm to my kids? I hate to ask but can I use this relationship to get fairer custody of my kids - I now see them Thur - Sun every week but would prefer a week on week off arrangement. STBX will not agree to this.

Can I get a restraining order placed against this man? FWIW, this man is the very reason our marriage dissolved in the first place. I’d pursue AA but he zero net worth. And I don’t have the $$ for such an expensive suit.