I (F22) have a boyfriend (22M), but have developed feelings/a crush on another guy (21M)

I go to university and have been doing some group work with a guy that I’m taking classes with. We have a really good chemistry and a couple of months ago I realised that I had started developing a crush on him. I’ve felt a lot of guilt. I’ve tried distancing myself from him as much as possible, but I see him on a daily basis so it’s been hard to avoid him. I truly love my boyfriend and I’ve tried spending more quality time with him as I thought that it might’ve been a lack of connection between us that had caused my interest for this guy from my classes. We’ve also been together for about three years so I guess it’s pretty normal for the spark to fade and for both of us to notice other people more than we’ve been doing before.
The crush/feelings or whatever you call what I felt and still feel for this guy had actually started fading a bit after distancing myself from him. But every time he talks to me I feel it again and instantly feel extreme guilt.
Now the guy from my class have actually started dating a friend of mine which is why all of this has been triggered again. I felt sick to my stomach when I found out. Mostly because of the guilt I felt for feeling sad about it.
I haven’t talked to my boyfriend about it and I am still not sure if I should. I don’t know if my mind is playing tricks with me, making the crush larger in my head than it actually is. I don’t want to unnecessarily hurt him but I also feel guilty for not telling him.
Has anyone here been in a similar situation or have any sort of advise of how to handle these emotions? I would also like to hear an opinion of whether its a good or bad idea to talk to my boyfriend about it?