My 'straight' friend told me he 'likes' me...

I've know this guy for close to 5 years now. He's my best friend, we work together, and spend a lot of time together. He's know I'm gay for all that time, and since then he's dated women and had a girlfriend for almost a year. I've had a crush on him forever but it was closer to a celebrity crush-he was cute and charming but I knew it would never happen. Until this weekend. I went to his place and he said that, while he still considers himself straight, he likes me. He say he misses me when I'm gone, thinks about me a lot, and pictures he and I together. Then he asked me out on a date. I was at a loss for words, and I told him I really just needed to think about all of that. He seemed hurt and we haven't spoken since then. I'm still trying to process it all. If he was gay/bi or whatever I would jump at this opportunity. But...I don't know what to do. Help!!!!