Do you tell ?

[GambleGamble]

Background:
Jack and Mike are really good friends

Jack dates Jill for 3 months over time gets meh about her they break up, we are all friends with this girl even before they begin dating...Jack says he doesnt give a damn about anyone else pounding her, states she is open game

Mike starts hanging out with her more and more about 2 months later....we see them hanging out and talking a lot no big deal we assume eventually they will hook up, which they eventually do....Mike starts to really like girl and openly admits this to me personally...

Couple months roll by til last night...big party everyone hanging out...Mike has to go work at bar we all go to...bunch of people end up there including Jack and Jill....who chat at the bar for first time in a long time...Mike is visibly annoyed

Jack and Jill disappear, Mike goes to piss...out walk other Jack and Jill, they state they were just talking Mike is obviously pissed.....Jack leaves, Mikes refuses to discuss with Jill....

...next day arrives and Jack is riding with 2 other friends unaware of situation, and states he [censored] Jill in bathroom of bar last night...Both call him and scumbag...tell friend of ours who relays said story to me...I tell roommate who also is friends with everyone involved and says someones gotta tell him....I said no [censored] way?

So OOT do you tell Mike that Jack [censored] his "girl" or shut the [censored] up and let it sort itself out...assuming your allegiance is the same to both guys??

...names have been names to protect the innocent

CLIFF NOTES:
Jack dates/[censored] girl, they break up Jill dates/[censored] Mike...during relationship Jack [censored] Jill in bathroom of Bar...do you tell Mike???