Help. Moving in with boyfriend... And straight best friend crush.

I am 18 and have been in a relationship with my boyfriend (19) for a year now. For about double that time I have been best friends with an older guy (23; I am friends with older college guys because I am a musician and know a lot of people in the field locally).In less than two weeks I am moving in with both of them in a two-bedroom apartment. I love my boyfriend and find him very attractive and satisfying still like I always have, and we have never had any problems. However, as I have been friends with my straight friend, I have developed a crush on him. It is half parts sexual and half emotional — doesn't help that he also looks pretty similar to my boyfriend. I know it won't work — we're open with each other, all we've done is cuddle (I was cold!) while cross faded a couple times. However, I still find myself thinking about us hooking up and now we are all going to be under the same roof.What do I do? How do I stop fixating on him? Do I pursue it further? My boyfriend is already suspicious of us but I've assured him he's straight — then my boyfriend brings up that means nothing.Yeah, I know I'm horrible. I don't want to cheat. I just don't know how to navigate this.