I'm happy that one of my best friends got an std
Why would you be happy your friend got an STD?
He's been an asshole to me lately.
You shouldn't be happy your friend got an STD. You should encourage your friends to practice good sexual health if you're concerned about their status.
Why not, he should get it.
This could be life changing for him, depending on the STD he got. Don't let petty vindictiveness cloud your thinking.