I saw that pyscho today. Had not seen him for 8 years. Hope we'll never cross paths again

Let the guy be Peter and my other camp-mate be Ben.

[Act 1]
Ben: Hey Peter, why got a lump on your forehead?
Peter: Don't ask.
Ben: Why like this?  People concerned ma.
Peter: It's ok.  Don't ask.
Me: Looks like the size has gone down.

[Act 2]
Peter: JW, you got a moment?
Me: I'm busy with my duties.  What is it?
Peter: Just come with me.

-moved outside of the restroom and grabbed the front of my vest, shaking me.

Peter: What do you want?  What do you want?

-
He's not a real pyscho, just one who thinks everyone was mocking him.  Though with that threat of physical violence, ended our friendship, if there ever was one.  I saw him today, a much cheerful person.
We did not acknowledge each other.