What I’m thinking is if her license is taken off her and if you live close to her you arrange it so she still has off weekends with him BUT you pick him up and drop him off and you’re to be advised of any driving. Perhaps even requesting her to share her phone location with you. During weekends you can share custody by having supervised visitations. So that way the baby is still getting quality mum time but you’ve put restrictions in place to protect your son. THEN get prior agreement that states if this happens again only supervised visitations will be allowed. And your other conditions. That way if it goes to court you can say you tried to be flexible. Just an idea.