What do I do about the fact that I met with an old friend today and now I can't stop thinking about him?
What did you do with him today?
We met up at a movie theater, watched a movie
It's good to think well of your old friends. Good friends can always make our lives better.
I want to go to a party with him and have sex...
Well, if you are interested in your friend then there's nothing wrong with that. You should let him know how you feel.