Do I act like I know nothing or tell her I know everything and exactly what I think of her?

"My first job was a horrible one, I had a lot of problems with my manager, so did everyone else but I was because I was her 2ic it meant I had to deal with it the most and when I raised that we had an issue by making a meeting with her and the regional, it got worse and no one listened. I was transferred to another store (for no particular reason, they do that with managers and part timers in low profit stores) and my manager went to a different one (I also had the option to go to the same store with her, I said no.)"

Quite a run-on sentence. You continue to prove that you're only marginally literate.

You're inability to get along with multiple manager indicates to any reasonable person that it's you. Fix your attitude. Combine an improved attitude with no longer crying at work and your employment prospects might improve.

Your call. But if you really want to mess with her, make up an even crazier reason why she was fired and let her explain the truth. "No, I didn't sht on the break room floor and leave it!" You: "Oh, so why did you get fired then?" She will prolly lie. Then you can say, "I was just messing with you, same way you messed with me. I know you stole that money." And walk away head held high lol.

Or say nothing and be productive with your life, which is what I would do.

Lets hope by the time you do have to speak to her you mature to a level to see how petty such a comment would be, and realize its based upon unproven gossip too. Would you like to be accused of things you were rumored to have done too by random people in your past? Karma works in different ways. Let it go and move on with your life.