Block her from being able to text your phone. This is someone you should interact with as minimally as possible. You can't control your husband's boundaries. Concentrate on your own. Even though you have become a couple, you each need your individual zones of control.

It is very tempting to think your lives would be so much better, if he would just do this or that. You have to somewhat let go of that. I would listen patiently, if he talks about how he can better manage this situation. But he's the one who has to decide what to do.

Your role in those kids' lives has to be that of grown-up friend. Don't try to assert authority over them.

I would suggest that you have a facebook page that is your own, which she is unable to access. Pictures of your boyfriend and you can be posted there, where they'll be viewed by people you and he are on good terms with, who value you as a couple. Let him have a facebook account for him and his kids that his ex-wife and her family can view, without bumping into photos of you. At least for now. Someday you may make a commitment to him through marriage. You may decide to cohabit with him permanently. Some things can be modified as your relationship with this man develops. Right now, you're a girlfriend. That means there needs to be a healthy distance between you and his ex-wife. She has no business contacting you about anything. Don't let yourself be an easy target for her attacks. Create a space between you, so that she does not impinge on what belongs to you.