Conflict advice?

Okay so there's this kid in my college BIO class. (I'm pretty sure he's a high school student, I'm not.)

This kid is an ass hat. First off, one day when we were cleaning after a lab, he refused because "that's what janitors get paid for." Some of the kids where giving him a hard time for it so I did too. All I said was "don't let your mom know! Haha" and everyone laughed. He got super pissed and said "don't let your mom know you're an f****** bitch!" I walked away because like "geez, sorry?" Maybe he doesn't have a mom? But Now whenever he's in class all he does is brag about how good of grades he's getting which is annoying but this is my issue...whenever I ask the teacher questions or to too repeat something, he takes this big sigh and then I can here him mumbling to his friends about how stupid I am. (He sits behind me.) I've been trying to ignore it but it's getting to the point where I don't want to go to class and I don't want to ask questions. I've been thinking of saying something to the teacher, but I really don't want to make a big deal out of it because it's not like I'm going home in tears or anything. Plus, I fully understand that this world is full of mean people and you can't go crying about it every time. So I just feel stuck. What would you do?