As the others stated, there really isnt much information to go on. But, here's what I CAN say.
I've dated a bunch, and been in some serious and not so serious relationships. What I've learned is that if I ever treated a girl unpleasantly, I didn't actually respect or care about her. She was more of an interesting moment that would pass through my life, because I had no intention of keeping her around. Now of course, that may paint me as a horrible person, but even at my worst there is a threshold that shouldn't be crossed.
That being said, on the flip side to that is how I'd respond to girls who actually meant something to me. And some who still do. There is a difference between a cold joke that will satisfy the jokester regardless of the outcome to the butt of it. And then there are the jokes that mutually bring laughter and in a way, somewhat of a bond.
I'm a fairly blunt person, and I have a bit of a twisted sense of humor. So, it's not for everyone. Long story short, if it sounds like he doesn't actually care about if it hurts you or not, it's most likely because he doesn't actually care for your well being. That's a bit of a bold assumption on such sparse information. But, I tend to fear the worst to more appreciate the best.
Anywho, I'm curious as to what the actual details of all this is. Feel free to send a message if you'd like. Best wishes.