Read about emotional blackmail, which is part of what he is doing to you.

If he ODs after leaving you, that is his choice, not yours.

He is abusing you. Get a restraining order and/or have the police evict him.

If social services finds out that you are using could well take away your child. They might very well do that under the circumstances anyways unless you get rid of him.

If you can't do these things for yourself, do them for your child.