I just found out my Друзья boyfriend is cheating on her. what should i do?

Tell her, I would wanna know that shit if I was her.

tell your friend. if she finds out that Ты knew she wont forgive you. after she dumps his sorry жопа, попка come up to him and kick him in the balls, shin,etc. either way just kick the shit out of him for being a lieing douch

Tell her.

There's no point in rushing to your friend and telling her without evidence. Even the most trusty of Друзья will be skeptical and it could end your friendship. I would take things slowly and think out a plan beforehand.
Keep an eye on this boyfriend, talk to the 'bit on the side' he has. Be sneaky and try taking pictures of them together etc.
Then i would confront the boyfriend. Tell him Ты know what he is up to, and Ты WILL tell your friend. So he better get his begging knees on and make it up to your friend and never ever do it again if she forgives him.
Then just sit your friend down, and gently explain that Ты needed to be sure before Ты told her.

Tell her, and go on the Maury Показать to expose him!

tell her she needs to know

Tell her, but I also wouldn't have asked Болталка strangers for advice.

tell her so she can dump the cheating douchebag on his жопа, попка where he belongs! (tell her gently though)

try to talk to her boyfriend what wrong with him

then SLAP him on the face LOL i was thinkingof doing that

Tell her.

Then go over to that bois house and хлопать, привкус the living sh** outta him.

I was jk about the last part.

Get Chuck Norris.

Let her know?

Tell her. If she doesn't want to listen, she isn't your friend. Give her the cold shoulder if Ты have to.

Tell her. Ты could also tell her boyfriend that Ты know.

Well since it seems like Ты have valid evidence, Показать your friend right away. If Ты don't tell her, it will only get worse. If she doesn't believe Ты (whyever that is...) then just leave...there's no point in having a friend who won't believe you.

I c u сказал(-а) u have evidence tell her if she doesnt believe u Показать her the pic and ask the other ppl tht know

go find the person who your Друзья boyfriend was cheating on and tell her "the boy u were hitting on has already got a girlfriend so call it of" if they dont talk with the boyfriend and remind them they already got a girlfriend

Ты have to be brutally honest. Друзья that hide the truth are the ones no one wants.
He shouldn't be doing that to his girlfriend; and that was wrong.
If your friend doesn't believe you; Показать the evidence.
And if she still won't take it; Показать the evidence up his жопа, попка или humiliate him by posting it on a social media site.
It should teach him a lesson. :)