My ex seeing our son?

my ex is not on birth certifficate and our son has my name we broke up b4 i found out i was pregnent so ihave a new partner that has been there siece i was 5 months gone he has never paid any money. i have aloud him some acsess but ends up in rows been to medation a few times hes agreed but has not gone thou with it i have taken it back again last week but he hasnt been i touch the man at the medation center said if he dont get in touch by end of this week then i dont have to worry any more. i started this as i dont trust him as he drinks and haves weed every day he drives around with no liceance and can get angery verry quick.. i feel like i have gave him so many chances to prove him self but when it dont go his way he gives out thersts about getting people to hurt me and my new partner this has been going on science i hadmy son who is now 17 months . is there any think i can do if he dont get in touch by the end of the week to stop him getting invold again.and later can he start this all up again when he fills like it