help please?

Wasn't sure where to post this, My ex was very violent, he never hit me but he punched Walls by my head etc and was very scary and one day when I was about 10 weeks pregnant he wouldn't let me past him to leave the house and wouldn't let me go until his mum came and pushed him away from me, anyway we broke up and I had the baby, and now almost 7 months later he's decided he wants a dna test and access but I've been told by his sister that he's on drugs but we don't have any proof, what is his chances?? I'm in the UK