What has worked best for me is to have no contact. I did see H twice in 3 weeks (no, we don't talk on the phone, text, e-mail etc) b/c of D13's performance and I was not feeling well and was at home when he came to visit D's. I can tell you that I will not have any contact in the next several weeks either. I'm not doing this to get any kind of response out of him, but so I can get my own stuff under control.
I know your kids are younger than mine and it may not be possible for you to have as little contact as I do. It has really helped me to put things into perespective and to take care of myself.
I know you have to deal with everything and it isn't fair. It's stressful and you need some kind of outlet. Any ideas?