Stop talking!!!

Hi. I'm an 18 year old girl. Over the summer I've had many partners no solid relationships just casual sex. One of the guys (my favorite) is older than me (26) and he's really really good. I love having sex with him and we both don't have feelings for each other, or at least we don't want to date. He's good at dirty talking and such but lately he thinks it's funny to jokingly compare me to other girls he's with or has been with. I'm all for being called a slut in bed but it makes me feel really bad when he talks about other girls. Like low key jealous and I know I have no right to be but I really want it to stop. How do I bring that up without sounding like A) I'm jealous B) that I want to be exclusive with him BC I don't.