Who cheated first on who first?

Question

Who cheated first? Addison or Derek? I distinctly remember Addison telling a patient that she was the one who cheated first, but I dare not trust my memory. This is crucial for my fanfic.

thanks.

Answer 1

addison cheated first...we are talking about grey's anatomy right?...lol

Answer 2

Yeah, she cheated first.  

Answer 3

Addison cheated on derek first with dereks best friend mark sloan, that's why derek moved to seattle but then she followed to try an win him back.....

I'm totally addicted to that show..bought all the box sets lol.

Answer 4

Yes. She cheated on Derek with Mark.