Junkie -
Tough situation, man, and I feel for you. Back when I was not-so-young but still incredibly stupid, I failed even to address problems in the relationship and let things slide. My story did not end well, but based on what I now know, and am still learning, I will offer my prayers now that I know who is really in charge of my life.
Don't know if this will help or hurt, but there is a national simulcast next Sunday IIRC about marriages and how to make them work. If I were married, or engaged, I would be there. Hard to admit even my my (advanced) age that I don't have many answers, but I am willing to learn. So it may help you as well.
Both of you need to go slow, and work in mutual love and understanding - for your own sakes as well as the kids. The alternative is too easy to obtain these days, and too destructive on everyone. There is a reason that God hates divorce - it is that destructive.