Taryn I completely sympathize with that fact that this situation requires you to have contact with your STBX. I know the feeling too well. I avoid things because I don't want to deal with him. Any contact I have with him just opens the door for some type of comment or remark to chip away at me with.
I would provide what I could and tell him that is what you did. I know you are trying to protect your kids and make the situation for them comfortable-but you are doing all you can. It will have to be enough. I would carefully plan what I was going to say-so you don't give him the opportunity to use anything you say to hurt you.
Good luck.
-------------------- Message for my ex "I think you know by now, I'm not the person I used to be"