AITAH for sleeping with someone else?

I 21F ghosted my ex boyfriend because he kept standing me up. He would set up dates and not follow through on them and he would keep me waiting throughout the night waiting for him to arrive, just for him not to show up. He would do this on multiple occasions. He would never even text me that he's canceled.

I ghosted him for a while because of this and slept with someone else and went on a really nice date with someone else. My ex boyfriend managed to get in contact with me through another number, and we started talking again. He said I'm a cheater since we were technically still together even though I ghosted him, but he said that there was no official text or call or me saying we're through or done, so he's saying I cheated. He proceeded to call me a 'fucking hoe' multiple times. And that he fucked me out of pity so I can have a sex life. He said my pussy was okay, and that he lied throughout the whole relationship saying I was the best pussy and tightest pussy ever.

He also texted me I'm the worst fuck ever and I was a pity fuck. To me, we were already done since I ghosted him. But AITA since I slept with someone else after ghosting him?

I was already done with him since he kept standing me up, and ghosting was the nicer option. So, AITA?