Just wanted to say I'm so sorry you're having to go through this. I know what you're going through and I think you're doing fantastically well. I have no words for how devastating the whole thing is. The lies, the promises, the betrayals, the sickening feeling over and over again as you remember times when he must have lied to you. Oh god, they lie so easily! I was amazed at the ease with which he must have look med in the eye and lied to me about where he was going and what he was doing.
I made the mistake of taking my ex back and believing his excuses at first. We didn't have sex for most of our relationship because he said he had a low sex drive and promised it would get better. In reality, he just didn't fancy me and was shagging other people behind my back. He was with me because it was like a ready made family for him and because I was stupid enough to put with it. I supported him financially a lot of the time even though I didn't earn much more than him. It's been three years since he left and I'm glad it's over.
Soapbox was right in that your feelings will change over the coming weeks and months. You need to think only of yourself and the children. Do what you need to do for now and don't feature him in any of your future plans. If you make it work together then you can always adapt those plans but if you decide to kick him out then you will have a kind of path mapped out already. Not too soon though. Take your time.
Oh yeah, I had Kelis (I Hate You So Much Right Now) on repeat, amongst other soppy stuff that I can't listen to any more, but that Kelis song is fantastic for screaming along to.
Kelis - Caught Out There
I just listened to it and got a bit as I can still remember the feelings I had when we were splitting up. Such rage and overwhelming sadness all at once.
You will get through this. This thread has some brilliant posts and advice as you have found out. It's just a shame so many of us have such bitter experience to speak from though.