I've been feeling strange emotions around a friend and what do I do

I help run a website online and lately one of the other site administrators has been giving me warm feelings. The man's name is... Well I'll just call him BR. BR is a very nice person to me and while I am a straight man, I can't help but fantasizing about him. I've talked to him about this and I think he might feel the same way. He says he's running for president so once he becomes one, he's going to give me citizenship. I love my fiance and all but I can't resist thinking about what it would be like with Brandon. And ever since I lost my job over the whole wrench incident, BR says he wants to give me a job in his administration. What do I do? Do I chase after BR and give up on my relationship with my fiance? I'm just so confused right now. All my life I thought I was straight but anymore I just don't know. La paz amigos.