How old are your kids? My youngest was 4 when. I left my ex. He never asks about his dad, and rarely wants to talk to him. We do send things in the mail. He is frightened of his father. Kids understand more than you think, even very young ones.
Your job here is to protect them. You can't even leave them alone with your husband, so you are basically a single parent right now. You have more options than you're allowing yourself to admit. I understand that most of them are not the hopeful outcome where your husband gets clean and you all live soberly ever after, but you do have choices. Just not choices you like.