Why did he say such hurtful things?

I was seeing this guy for over a year and he suddenly stopped texting as much and when I asked him what was going on he said he was hanging out with some girl but he didn't want to lose me out of his life. I was really hurt because he'd said he wanted to be single and didn't want a girlfriend because he wasn't ready to settle down. Then on Facebook I see they're in a relationship. I was really hurt especially that i'd found out this way so I sent him a message saying all the things I felt it I did say I wish he'd never messaged me in the first place and he never cared about or else he wouldn't have lied and cheated (which he did I found out recently) to me. He then sent back a really cruel and abusive message saying that we were never anything and that he was on tinder the whole time we were together and that he done nothing wrong and he was going to stick by that.

Why would he say that? When obviously I did mean something to him. We were seeing each other for a year, he said he cared about me and cried when we said goodbye to each other when he moved, I was only ever good to him. I just don't understand.
It hurts me that he could be so cruel.
Any insights?
Why did he say such hurtful things?
Add Opinion