To feel like you were getting close to someone and then you find something out about them that is deceitful.
He was so sweet and I bought it. Now I'm done. I see you. Don't be sad, it's your fault- go cry me a river.
Exaggerated way to show disinterest in a subject that somebody cares deeply about
Person A: "My favorite tv show is cancelled"
Person B: "Cry me a river so I can swim away"