Do I tell my guy friend?

Ok so my boyfriend and I broke up when I moved away for school and now we're getting back together. He's going to be visiting me in a couple weeks for the weekend. The only issue is that I have this friend in my program. We live in the same building (he's two doors down from me) and we study together pretty much every day. He's a great guy, but he has a crush on me. He asked me out a month ago and I turned me down stating that I wasn't over my ex and until I was I didn't want to date anyone. He's defiantly going to see and probably meet my ex just because our school schedule is identical and we see each other so much. I don't want him thinking I just told him I wasn't over my ex because I didn't want to date him (I really would've considered dating him if I wasn't still hung up on my ex). I don't want to hurt him. So I'm thinking I should tell him about my boyfriend visiting and who he is but maybe I should wait till they meet or something?