I hope this helps you and others. I am providing a resource for information about drinking. The fact that your boyfriend appears to have a high tolerance for alcohol is actually a worry.

Rethinking Drinking Homepage - NIAAA

This family has multiple problems and your healthy approach to life is not the bandaid to fix them. I have seen this before, where a man or woman with significant problems will attract a healthy mate with a compassionate heart -- but unless the person with the problems wants to make changes the relationship is going to be heavy going.

I would cut my losses and not pursue a romantic relationship with this man. If you think you could create a friendship with him (and his ex-wife) you might still be able to be a positive influence in the children's lives. Also if you are looking for positive influence on children; please consider being a Big Sister or adopting an older child who would be so grateful for a home.