I just found out my 프렌즈 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 당신 knew she wont forgive you. after she dumps his sorry 나귀, 엉덩이 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 프렌즈 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 당신 know what he is up to, and 당신 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 당신 needed to be sure before 당신 told her.

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

tell her she needs to know

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

tell her so she can dump the cheating douchebag on his 나귀, 엉덩이 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 헤로인 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 당신 have to.

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

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

I c u said u have evidence tell her if she doesnt believe u show her the pic and ask the other ppl tht know

go find the person who your 프렌즈 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

당신 have to be brutally honest. 프렌즈 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; show the evidence.
And if she still won't take it; show the evidence up his 나귀, 엉덩이 또는 humiliate him 의해 posting it on a social media site.
It should teach him a lesson. :)