It sounds like there's a lot of issues there outside of his drug use. If there's no love or if he's a danger to you or your children (even if he doesn't mean to be) then you are probably better off far far away from him.

I couldn't help notice you said you felt "betrayed" by his drug use. While that's valid I have another perspective to offer.

When I met my wife she knew I was a heroin addict. When I tried to be with her she made me promise to ditch the drugs or she didn't want to be with me. I did ditch them...for all of 6 months. I started sneaking it around and shockingly I remained functional and was even able to hide it from her for years. Eventually I did get caught and it was a disaster. She told me she felt betrayed too. Fact is, my drug use was never about her. It was all about me and my baggage. Although it hurt her, she was not part of the reason I used at all and I never understood why she took it so personally. Selfish, true but in my opinion you can't take an addicts choices personally. They're usually only thinking about themselves.