This woman found out the hard way about her boyfriend’s infidelity -- from her neighbor.

A woman received a harsh note on her car suggesting that she break up with her boyfriend.

The note, which was photographed and posted on the Neighbors From Hell Instagram page, explained that the neighbor knew about the boyfriend’s infidelity because she had actually slept with him herself.

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“FYI: I f---ed your boyfriend,” the note said. “He said you were broken up.”

The neighbor, who appears to live in the same apartment complex, also listed two pieces of advice for the woman, which didn’t strictly stay on the topic of her cheating boyfriend.

“1) Wash your car,” the neighbor wrote. “2) Dump him (not in that order).”

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The post on Neighbors From Hell, captioned “Everything comes out the wash," has received tens of thousands of likes and plenty of comments since it was posted last week.

A woman received a brutal note on her car from her neighbor who said she had slept with the woman's boyfriend. 

A woman received a brutal note on her car from her neighbor who said she had slept with the woman's boyfriend. 

Many commenters said they would have appreciated the note and the neighbor who wrote it.

“Best neighbor,” one person wrote.

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Another person commented: “Who ever [sic] this is, I need her to be my best friend.”

And another person wrote.“Honestly, this is the kinda neighbor I would like to have."

One commenter said they had actually done something similar before.

“We became best friends,” the person said.

Someone else suggested that the neighbor should “at least wash the car for them…”

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