Why does it have be this way?

Why is it, when people get divorced, they can't get past their "history" and just do what's in the best interest of the child(ren) involved??? Is this the million dollar question, or what?!

Ben came to pick up Lily tonight...last night we "discussed" my wishes that she be home each Sunday to go to church. I guess we decided that she'll go to his house every Friday night and come home on Saturday. When I first said that I wanted her home for church, he got mad and said, "its in the papers that she's to stay with me until 6pm on Sunday nights [the oh-holy-papers DO say that, but they don't say she has to go every other weekend; only that if reasonable arrangements can't be agreed upon, she will be with him "at least" every other weekend]. What I still can't get over is that he actually had the gall - after being unemployed for nearly 3 months and being 3 child support payments behind - to bring up the papers. In all this time, I haven't once said to him, "Ben, you know it says in the papers that you're supposed to carry insurance on Lily" or "Ben, the papers say that you're supposed to pay me support". I haven't even brought up the damn papers. Yes, I have taken every (single) opportunity to make him feel bad about quitting his job (he still says he had no choice, but no one put a gun to his head and made him quit); but I have never - not ONCE - ever mentioned the possible legal ramifications of him quitting his job.
So, I called him back last night and asked him - nicely - why he was so quick to bring up the papers. He wouldn't talk about it. So I told him we'd talk about it today; and we did. He didn't like that either, and to make a already too long story short said that he was going to make sure my child support would go through the state so I would only get the bare minimum. Nice huh? I am so mad right now that I can't really even think straight.
I really hate him. God help me, I know I'm not supposed to hate him, but I can't help it right now...so cut me some slack.