Any advice?

So one of my best friends Salena has decided to become transgendered. She says that this is all she's ever wanted, and that she'll finally be happy. I don't care; I'm happy for her. Or him, rather.

She decided her name will be Sam, and will start taping down his chest. (Compression shirts are to expensive for his family right now.) And, because of this, Sam has asked me to work out with him so he can drop some pounds. (He weighs 220 lbs., but doesn't look it.)

Anyway, we go to the park and start to jog until we finally decide to fuck it and just listen to music and lie on a bench. We play Twenty Questions, with things questions like, 'Where's your favorite place in the world' and 'How do you want to die'.

Throughout this, Sam begins to subtly flirt with me. He eventually admits to always liking me, having thought about dating me, and even hinting that I'm his dream girl. He even said that he's thought about having sex with me-romantically. (Says it would be an 8.5 out of 10.)

He said, and I quote, "I know exactly how to sweep you off your feet."

I don't know what to think. I'm not attracted to Salena, but I don't know about Sam. I've always dreamt of someone confessing their long time love for me, but Sam never came out and said he loved me. In fact, he never even made a serious pass at me.(He did not ask me out.) Plus, I'm sort of involved with a girl named Austin, but that's complicated.

Maybe I could end up loving Sam. I don't know what to think. All I know is that I am not interested in Sam as a girl, but with him as a boy...

Part of the problem is that we know each other very well. We like the same things, have generally the same humor, and can speak with each other easily.

So what do you think? Should I just blow him off or should I tell him I'll consider it?