Wth. I just don't understand.

Can someone please tell me why whenever my ex and I break up and are fighting he says hurtful things to piss me off like.. "Getting laid gtg" or "you're not what I want. What I want is beside me." Etc. do you think that there's any truth to it? Or is he just trying to piss me off or say it out of anger? The getting laid one he told me wasn't true and that he was mad. But the second one he said tonight and then he took the time to send me a message acting like his "gf" and it was super long. It kind of sounded like him but idk if it was or not. He used to always text a convo to himself acting like him and another person and then screen shot it so I really don't know if he's serious this time or not. Any ideas? Obviously I don't want to talk to him about it because it's upsetting and I just want to move on. Plus he probably wont even answer anyway as he's too busy drinking every day.