You're going to have to let him go Cindy, you can't control your H, you have to let him go to get H back. It's the only way. No matter what happens, for yourself, you need to be happy, your boys need to be happy. They do not need this, H is their father yes, but my C told me that the kids needed to be with the one that was the strongest...and that was me. Your children need the stability which doesn't mean they can't see their father, but it sounds like H is only available when H wants to be available anyway. Cindy, you need to get strong, you need to be happy, you need to let him go in your heart and work on you, that's all we can do when this happens.
I hope I'm not sounding harsh and I'm not telling you what to do either, just suggestions. It's a hard decision, but one that has to made by you.