You did great. I agree with everyone else that everything your H is saying is PROJECTION. Ofcourse he was going to get defensive. So does every CONTROLLING person when they dont get there way.
To answer his question "why didnt you wait till after the Holidays???" Answer: Because I've neglected myself for way too long and now I'm doing something about it. Remember, like with kids, practice Love and Logic. For adults "Im sorry you feel that way..." For kids "Im sorry for you. You made a bad choice..." Your H is somewhere in between. He made a lot of bad choices and now it's time to take BACK CONTROL of YOUR LIFE and hold him accountable for those choices.
Dont worry about the kids. They will be fine. Remember they dont know what you know. Which is good. They should be innocents in all this. Your job is to protect them. Dont worry about explaining yourself. The truth will come out in the end.
Just stay strong and know that this was LONG OVERDUE. And also that you are NOT ending your Marriage you are CHALLENGING your H to DO what he vowed to do in the first place. To RESPECT, CHERISH, LOVE, etc. You are giving him a CHOICE to "MAN UP". If he doesnt, then like you would a child, reply "Im sorry for you. You made a bad choice... Now it's time to take responsibility for those actions.
To be honest I am more worried about your H realizing your true intent and to start playing Mr. Nice/Reformed guy that will give him another chance. You are too vulernable for this right now. The best thing you can do is set BOUNDARIES for yourself. Tell yourself that you will do nothing for at least 6 mons or so with H. Dont let him CONTROL or MANIPULATE you.
Remember YOU are the ONLY person that YOU need to JUSTIFY this too. Dont feel you need to explain anything to anyone especially H. Just reply like you did "I just NEED space and time. Hopefully YOU will CHOOSE to RESPECT that."