I agree with Tulip. I think you need to sit down and talk about where his anger is coming from. I understand that the ride started off on an unpleasant note, but it seems like his anger was about more than the jerky people in the parking lot (especially the "there's your boyfriend" comment- that's his ego talking).
Maybe it's jealousy that you're doing something athletic and he can't keep up, maybe he's worried you'll love to ride so much you'll get a new set of friends and he'll feel left out.
Definitely talk to him about it.

When I started riding, I rode a lot. My DH eventually got tired of me doing things without him and he bought a bike, too, so we could do it together. Now he's so fast I can't keep up with him, and even though we rarely ever ride "together," we start out at the same time and he comes back to check on me. It's something we both love and he doesn't feel left out anymore.