my ex passed out at xmas from withdrawal about half an hour after getting to a playcentre having drove dd and a friend there, she saw him and was so worried, had to call friends to get their kids and her and went to hosp with him. will never forget it, we don`t have any formal visitation stuff in place as yet so cant advise you there. am thinking of you and know how horrible it feels.
document everything you can and try to protect you and DD as much as possible, (((((hugs))))).