In a relationship but crushing on someone else

So I've been in a relationship with my boyfriend for just over two years now. I love him deeply and I know in my heart he is my soul mate. Our relationship is not exactly "open" but we have each messed around with other people twice. We've always been honest with each other about this and talked about it before doing anything. We both firmly believe philosophically that strict monogamy is not innately human and have always been receptive of each other's sexuality.With all that said, I find myself having feelings for another friend of ours. I've always had a small crush on him and he's come over to our house a few times (with other friends) and we've had small "moments" where our arms touch and we let them sit there or he'll like rest his head on me or something stupid. Now this guy as far as anyone knew was 100% straight and hangs out with "the boys" and casually dates girls and all that, so I never thought anything of it and I dismissed any fantasy that these "moments" might have meant anything. And you know how we are with our straight friends (especially the ones you like) where you act like you're not into them when in fact you might be and you push them away when they're being "gay" or whatever.Here's where shit starts to get interesting. Last week during an acid trip he confessed to me, my boyfriend, and his best friend that he's probably closer to pansexual. Now I've always been honest with my bf about my attractions to other guys and he's even completely aware that I have feelings for this guy, but him coming out to us stirred something in me. I want him. The funny thing is my bf is into him too, though I might be in a little deeper. Lately I've been noticing some things, though, and now I'm pretty sure that this guy is into my boyfriend and I have no fucking idea how to feel about this. I won't go into details but my boyfriend feels it too.This is all just so confusing and so crazy that I don't know what to think. First of all, why the fuck do I have feelings for another guy if I'm happy in my own relationship? I guess I understand that it's only natural but I don't like it. It makes me feel guilty and dirty. And second of all, wtf am I gonna do if it turns out that he does like my boyfriend. It hurts to even think about. I'm jealous for both of them. I can't even look at him without feeling this like painful hole in my stomach.Wtf do I do guys? My head hurts.