Hypocritical classmate spreads rumors about me being a flirt

Back in secondary I had a lot of friends who were girls (either from same year or juniors) they would often ask me to wingman them cause they had crushes on my guy friends and they would describe me as a brother for hooking them up.

Starting my course in college. I Would occasionally see some of the girls during school hours and would have some small talk. some of my guy friends would be there sometime, but not everything is going so smoothly recently.

my classmate(22M) been spreading rumors about me, saying Im a flirt to several girls. Some of the girls I know through friends and some I don’t.

My classmate would then start openly flaming me about it. Infront of the whole class saying “Your honesty such a asshole, unlike you im loyal sticking to one girl”. Some of my classmates already know he’s trying to stir shit.

This where it starts getting a little hypocritical.
So for the past idk how many months, he’s been trying to get together with his ex and everytime its a no. So he switched to another girl immediately but it didnt worked out cause the girl was too busy with school.

A few days later he switched over to one of the girls who he tried to white knight who was apparently 17 and fresh out of secondary only. That was when I told him it was a very bad idea, even some of my other classmates jumped in agreeing. He’s response was that age was just a number type shi- and if he couldn’t get with her he would just date one of the girls he’s been clubbing and texting with.

Sure I understand how me being friendly with my old female friends may be misunderstood as flirting to people I just met but how he talks himself up to be “loyal” when he openly admitted to switching girls with one of them even being underage just pisses me off