Ah, seems like y'all were a little more intertwined life wise, but this is very similar to how me and one of Ns interacted. Every time I didn't react after the breakup he just piled on the painful (or I'm doing better than you/you must be miserable and sad) statements. You're reacting in a normal way, he sees you're not responding and ups the ante to get you to care/have a reaction. People with strong boundaries and self-esteem put their needs first - and that's what you need to do. So he says this or that - right now it doesn't matter because he declared that you are not his priority anymore, so he shouldn't be yours. Give/mail all his things, ignore all his baiting and go NC so you have time to heal.