Help a friend with MAJOR fiance trouble

[WTFomgWTF]

My friend recently dropped a HUGE piece of information on his fiance and he's been so devestated ever since finding out. Apparently, his fiance has had sex several times with her step-brother.including when she was on a break in the relationship with my friend. He doesn't know what to do and asked me for advice but my jaw is still dropped from when he told me about this two days ago. Im lost and have no clue. I thought this [censored] only happens in movies.

Background info:
Both are under 27. The sex happened when the two step-syblings were really young, but obviously the sex during the break was relatively recent. He loves her and she loves him... she doesn't know that he knows (I don't even know how he does, but he said he's 100% certain. Ive never seen him talk to me so seriously before.) Im completeley clueless and so is he, what would OOT do? Any piece of advice (besides jokes) will be relayed to the friend.

[edfurlong]

Seems fine, but I'll need pictures to make a final decision.

[Josey_Wales]

OJ

[bisonbison]

Once he calms down he should talk to her. Or not.

But first, he's gotta calm down and realize that this doesn't change anything about her.

[Scary_Tiger]

So she isn't even related to this guy? So she had sex with some other guy when they weren't together? This is a deal breaker?

[Hopey]

KKF?

[ridonkulous]

I saw this on an episode of "Lost". Tell your friend not to worry because they both die anyway.

[DrewDevil]

Is your friend named Greg Brady?

[KingMedicine]

my initial take is that step doesnt count in this sort of a situation, although it is a bit abnormal. without the blood relation, i just dont see the big deal besides the fact that she's going to be seeing bro-man throughout her life likely and yr friend is going to have to look him in the eyes knowing he banged his wife.
if the relationship is good besides this new info, id advise yr friend to let it go. if he has another good reason to want to get out of the engagement, this is his chance to bounce on her.

[Stagger_Lee]

Any relation to Woody Allen?

Unless your friend is winding you up tell him to run and don't stop until is is far far away from these nuts. Tell him not to even look over his shoulder in case she is following.