Hello Beautifulgirl,
My heart goes out to you. I understand. I was in a similar situation (I have only one child but in addition to our child, I felt like my AH was 5 kids when he was actively drinking & smoking pot). I had similar conversations with my AH and basically he was saying to me that he would not quit even if it was hurting him and our family. (I ended up leaving since he wouldn't leave and I didn't want any more drama. My husband got worse, hit bottom and then entered rehab.)
You have so much on your plate. There is so much you have to worry about. Your kids really need you more than ever. Sometimes we hang onto our addicted partners believing in all of their positive qualities (usually fantasies) and believing that our children need their father (or mother). What our children need is at least one sane, healthy, secure, loving, dedicated adult-parent. Don't be hard on yourself, Beautifulgirl.
You are doing the best you can. Keep reading. Keep posting. Keep listening to your Higher Powers. They will guide you gently toward the path you need to be on. And let your AH's Higher Powers guide him. In the meantime, take good care of yourself and those five precious children of yours who depend on you. You and your children are what matter right now.
I pray for you and for your husband, as well. Your husband will need to crash hard before there is even a possibility of recovery. As long as those substances are in his mind and body, his ability to care, to feel, to empathize, to love anyone (himself, his wife, his children,etc.) will be void. You know this and this is why you've set that boundary (no drugs!). . . he isn't ready yet. Maybe, one day, he will be. . .but it isn't today.
Beautifulgirl, please take care. Sending healing, warm thoughts your way.