Advice please. Sex with ex

Me and my ex still have strings feelings and still have sex often.maybe a few timea a week. We aren't together because we have terrible fights. Anyway.

Last night we were having sex and after I came, he stopped. Said he was tired. Today, I hit him up to come finish what we started and he says "no thanks " .

I asked him why he's saying no, and he tells me he came to his senses during we last night and all he could think about is " is this really what I want to be doing with my life at 28 years old?" Then he proceeds to call me a whore, and tell me that he has also been sleeping with the mother of his child. As I'm writing this, I'm starting to see the truth. Omg.