I'm a guy, and I met up with a guy online last night. We did things. We mively regret it. What do I do now?

Yeah, from what you said, it doesn't really sound to me like you have anything to worry about as far as getting an STD or whatever from the guy....but if you have any doubts, definitely go get checked out. And if you think you're really over the attraction to other guys, then just file last night away in your mind as a learning experience, and move on with your life. You shouldn't keep dwelling on it and worrying about it. I wish you had someone in your life (parent, uncle/aunt, older friend, etc) to talk to about stuff like this. Being a teenager is hard enough without trying to get through it all on your own! But above all, PLEASE don't ever meet up with anybody that you've found online. Everybody seems to agree that was an incredibly dangerous thing to do! Okay, I really hope things go better for you from now on. You sound like a good kid, and you deserve a long, happy, healthy life. Take care of yourself!