Confused..

So. I have a boyfriend, right? He's amazing. He treats me well, his family is nice, we hang out with his friends and mine. He's unlike any other guy I've dated and I love him to death. I'm happy in my relationship, beyond happy in fact, and I wouldn't trade it for anything in the world. The problem is this: there's this other guy, who I'm FRIENDS WITH. And I can't stress that enough, we're just friends. But we did used to have like a thing for each other. It never amounted to anything other than flirty texts and stuff like that because he moved, but we still talk and we're close now. The thing is, the other guy, we'll call him Tom for simplicity's sake(and we'll call my boyfriend Bob, not that he'll be mentioned that often), but Tom works a graveyard shift for his job, so even on his days off he's awake at night and asleep during the day. Because of this, he's the first person I text when I can't sleep at night or when I have a nightmare(I have PTSD and am awoken by nightmares on a regular basis) and on top of that we've been friends since high school. I've been on vacation and now Tom's nighttime is my daytime and I talk to him more than I talk to Bob. With all of that, I've developed what I think is(and hope is just as simple as) a crush on him. At least that's what my best friend is telling me, and she's usually right about these things😒
I just don't know how I feel about this. Like is this normal? Like I've been with Bob for over a year and a half now and I do love him with all my heart, but me and Bob don't ever talk like me and Tom do. And I just don't know what to do 
Edit: I want to reiterate that the reason I'm talking to Tom more than Bob is because I'm in a different country and my daytime is nighttime for everyone at home. Since Tom works overnight shifts at work, he's awake at the same time as me.
Another edit: I also want to mention, that I am not physically attracted to Tom in anyway, it's just like kind of an odd feeling I get when we text and it's my best friend who's telling me that it's a crush. While I still believe(and maybe I'm in denial) that we're just friends