He's SO mean and cruel!!

It's been 3 weeks of LC. It was really him that initiated it because he got angry at me for being unable to get back from out of town so he could drop our daughter off early. (I was riding with a friend who's car broke down 3 hours out of town. He says he didn't care if I was in a car that blew up, being a responsible mom means being home when he needs to drop her off! LOL)
She had her 1 year checkup at the Dr. Monday. At her 6 month checkup her iron was low so she had to be on a supplement. STUPID me, sent him a text today to let him know the Dr. called and all is well with her iron. His response was to tell me that he thinks my email has been hacked because he has received a few emails from my email address and while it's easy enough for him to hit delete, he thought I might need to reset my password.
The last thing I emailed him was about a month ago and it was the description of the narcissist relationship cycle I found online describing idealize, devalue, discard.
Today is the first time in 3 weeks that I've initiated contact and it genuinely was because I thought he might be interested in knowing his daughter is healthy. I was not expecting a response at all.
I just don't understand why he HAS to continue to be so cruel. He's gotten everything he wants...he left, I don't bother him anymore, he pays what he wants to pay in child support, he sees her when he wants to see her, and I'm still reeling from the pain of it all....what more does he want from me??