I’m stressed about a friend not respecting my boundaries

So I’m in college and a science major (19F). This is a fairly small major so I’ve gotten to know some people well. In particular a boy (20M) and two girls (19F’s) either from being in a lecture group together or having lab together. Admittedly, I was fairly close with the guy last year because not only were we lab partners, but also I was trying out a church youth group he’s a member in. I ended up leaving it this year as it’s not for me, but I saw him a lot in group hangouts. I guess I’d say we were closeish but also I only had one lab with him last year. I recently got out of this long relationship so last year I flirted a bit and even had a tiny proximity crush on him. Now, I’m very much not interested. The root of the issue is that now that I’ve left this church group, I don’t feel like I have a lot in common with this dude and I feel awkward talking to him because he’s always talking about this group. (I’ve realized I’m not very religious if at all.) I am trying to get closer to the two girls I know in the class too as we share the same values and are buddy buddies. The problem is that this guy is not catching a hint. I don’t mind if he sits with us in lecture or even gets lunch with us every once a while after. It’s that he doesn’t seem to know boundaries. He’ll sit with us fine but then we get dismissed and he just kinda follows us. He doesn’t speak that much either and we feel uncomfortable. It’s also really hard to dodge him because he just follows us. Today one of the girls and I ran through like a hidden path and around a building to avoid him while he chatted with someone. It seemed like we lost him and then we turned around and he was speed walking towards us with a scary pace. There really wasn’t anything to be scared of and their was plenty of people around but it still made us seriously uncomfortable. We only got away from him by going into the girl’s bathroom and he was waiting for us when we got out. We finally got away from him when he went to eat. It’s just this guy is in like 2/4 classes, so I see him everyday. He wants to sit together in lecture, wants to walk to and from it etc. i’ve tried to get their early or leave early but he’s always already there saving me a seat or he follows me. On another day he did that same follow thingy he did to my friend and I but it was just me. I was going down the stairs really fast because I had an appointment not 10 minutes after I got out of class. I was practically running down these stairs and idk why I looked back but I see him rushing towards me. It felt like I was being chased and now I’m genuinely uncomfortable and a little scared of him. Especially since he never announced himself, he just semi-chased me until I lost him on the street outside of the building. Admittedly, I’ve been kinda rude, avoidant, and giving the cold shoulder and I think he’s beginning to catch one but it still isn’t enough. He’s a really really smart kid and it seems like he has other friends, idk why he’s doing this but I just need it to stop. I’m going crazy and I even had a nightmare about it this week. Also he makes me feel bad about asking questions or seeing where others are in things like homework assignments. Saying things like “I already turned it in” or “It was easy for me” or “I’ll turn it in the day before the teacher assigns it”. It all just rubs me the wrong way and I want some distance.

TL;DR I’m wanting to creat boundaries with a guy friend in College but he’s not getting the hint and is beginning to unsettle me