I've been throwing out my ex roommates mail
Wow, how much have to thrown out?
About 3 pieces of mail and out of 4 bills.
It is annoying to deal with mail from somebody who doesn't live there, but you shouldn't throw it away. It might be illegal.
I want to be rid of everything they ever had.
You can talk to the post office and tell them they no longer live there so they can return the mail to the sender. If it is something important they might need it.