How should I tell this bitch of a woman off?

As everyone has said so far, let her fall. Some people learn things the hard way. It took some actual gangsters to physically beat me out of being a tryhard gangster back in Year 10. Although it lead me to a fucked up depression and although it's cultivated the way I think, I'm grateful that they bashed me up bad; I would've still been a dickhead.

If you do really care about her then maybe letting her find out the hard way would be good for her. And when she gets into depression (I'm not wishing it on anyone... It's really fucked up though) there would be the perfect opportunity to rekindle the friendship again. Of course this is all theoretically speaking as I'm not you.

As for the teacher... whoa shit man. Life sucks for you, bro. Messing with someone who has a relatively good grip on authority is dangerous shit and I recommend backing off until you know you can do something about it... But IMO I don't think you'd be ready for it yet. That's not to say you suck but truthfully, would you be able to mess with him and get out alive? Wait till you can do that before even CONSIDERING doing something.

Just ignore that bastard's comments. Know that you're still here with people who actually care about you and that you'll be getting a better job than him (you seem the smart type ). well, just know you're better off than him.

Jam it back in, in the dark.

"Run... Run away and never return" (Scar, The Lion King)

Um... yeh. In my experience just dissociating yourself from shit is the best way to go. Of course it'll be hard to completely avoid (unless the teacher dude gets struck by lightning...) the whole thing but move on dude.

Find another girl/best friend and then in the future, should she come back, RUB IT IN LIKE HELL. Okay, people here are telling us to be mature... Should she come back, just tell her to leave.

There's nowhere I can't reach.