Oh, Bird, my heart goes out to you! I agree with other posters that you've done the right thing, you're very brave, and should enjoy your new life. Please realize it's a classic abuser move to apologize and try to win back the abused - just so they can start the abuse all over again. Please don't ever fall for that, don't even think about it.
As for your children, I know this is a period of adjustment for them, and it may be hard. IMO, that's true in many divorce cases. I would just tell them that it's not a matter of "love," that you and their dad just didn't get along anymore and couldn't make each other happy. Also, please emphasize that it isn't their problem (he may be making them feel like it is) and that you both will always love them , no matter what. Oh and that you'll always want them in your life, regardless (in case they are worried about that) b/c they are your beloved children, period.
Surely, as time goes on, this situation will get better. Best of luck to you and keep us posted!