Search Results: worry about her cheating

So friend A and friend B are best friends. I’m friends with both of them, and there’s also friend C. We’re like a “squad” and we’ve been hanging with each other for a few years.

Anyway friend A and friend B are pulling a prank on friend C. Friend A (female) was the mastermind. Friend B (male) just follows what she tells him to do. Since friend C is known to be very gullible and has a low self esteem, A and B are taking advantage of it and they’re manipulating her. Friend B is pretending to be in love with her and he’s sweet talking her.

They ended up dating and friend C is unaware of how much they talk trash about her. I’m literally the one in the middle because I didn’t know they were pranking her until friend B told me, but urged me not to tell friend C. I’ve been very inclined to tell her because it’s getting to a point where they’re also acting like friend B cheated on her, and she got upset and it really looks like they’ve taken it too far. They are playing with her feelings intentionally. Friend A is hurting her and she brainwashes her too, saying “he loves you don’t worry!” And she got friend C to forgive him for “cheating.”

This is just too much. I don’t know why they’d do this to her. Should I tell her or should I tell them to tell her?