If you say that you are going to get evenwith someone, you mean that you are going to cause them the same amount of harm or annoyance as they have caused you.
[informal]
I'm going to get even with you for this. [+ with]
Don't get angry, get even.
See full dictionary entry for even
get even in British English
informal
to exact revenge (on); settle accounts (with)
See full dictionary entry for even
get even
to get your revenge on someone who has hurt or injured you in some way.
He is so incensed by what he considers shabby treatment that he's determined to geteven.
Examples of 'get even' in a sentence
get even
In one afternoon, Shel had removed both Emerald's identity and her security, yet she didn't waste time planning to get even.
Pacter, Trudi YELLOW BIRD
I had precious little to live for here; I just wanted to get even.
Forbes, Bryan A SONG AT TWILIGHT
It's taken months of submersion in sea-water to get even that amount of encrustation!