Please make him be responsible for his kids and set up a visitiation schedule now. It is unfair, and unhealthy for you to bear the parent burden alone continuously.
I never seperated but when the A was in full swing I was alone a lot more than not, and when he was there he was such an ass I didn't want to leave my kids with him. I told him at one point, at least divorced moms get a break once in awhile, I never do. The silence from him was palpable.
Anyway make sure he does some of the work with the kids. Also reach out to friends for support, and make sure you do one nice thing for you, and just you every day.