Need advice about my gay best friend!

I need help! I am a straight, single female with a best friend who is a gorgeous, gay man. Sunday night we went out and had drinks. He had more than I did and suddenly said, "If I wasn't gay, I would fall in love with...." then he stopped and said, no and shook his head. I'm just dumbfounded. We've been close friends for almost 6 years and have helped each other through many problems, including heartbreaks. We talk about who he's dating and/or sleeping with and he has never, ever said anything about women. He actually told me once he is almost 100% sure he is gay. We have mutual friends but last fall he started wanting to go out just me and him. We sometimes go to a gay club and one night he grabbed my hand. To make sure we didn't get split up, I thought. The next time we went out, we both got pretty tipsy. The next morning I realized we'd held hands all night... like fingers-interlaced-type of holding hands and a lot of extremely close hugging. At one point he even grabbed my face and pulled it to his but suddenly stopped and smiled. The club has a mix of different people and I get hit on sometimes by men. He started telling them that he was my boyfriend and having some possessive body language when I would flirt with other men. Of course, I thought this was best friend protectiveness/possessiveness, which I've felt too when hanging out with his friends. We've both struggled with relationships and with being hurt. I started wondering if he was interested in me but in the end I concluded that it must be due to loneliness and frustration because I felt an attraction to him too and decided that must be where it was coming from. Is that what this could be? I know he already put it out there that "IF" he wasn't gay...and I know he said he "would" fall in love not that he was in love but this is a man who doesn't easily fall in love or easily talks about love. For him to use those words is extraordinary. Plus this has been escalating for months. I don't know what to think anymore. Can a man who's always known he is gay fall in love with a woman?? I am fully aware of sexual preference fluidity but we've spent a lot of time talking about everything under the sun in the last 6 years and he has never expressed any interest in women. Please help.