What will you do? (Ethical dilemma question)

[bennyboy]

You have a friend. He/She is your best friend. You've been friends for a long long time and you're very dear friends.

This friend of yours have a boyfriend/girlfriend that he/she loves very much. They've been dating for more than 8 years. They are such a lovely couple hoping to get married one day. All they talk about is how many kids they're going to have, their marriage, their future, they're really in love etc.

One day you're left alone with the girlfriend/boyfriend of your best friend for a brief moment and he/she starts touching you, kissing you, feeling you up, like basically sexually assault you and immediately goes back to normal when somebody walked in. 

You're shocked. This person is nothing like you had imagined and you're left with two options:

1) You tell your best friend what happened. 
2) You don't tell your best friend what happened. 

What will you do? Why?

I am going to tell my friend to dump the ho. I know, btw, what happens next-- 100% the bitch will claim you hit on her and begged her to keep it a secret, and that she'd never ever do anything like that. Then your friend will tell you to fuck yourself and break off social contact. Then he'll figure out years later she's cheating on him, divorce her, end up a single Dad because it turns out she's been doing heroin again, and you'll take your kids and his to a hockey game some day.

To the guys who said they wouldn't appreciate the "sexual assault," I just can't get on that page; yeah yeah liberalism, women and men are equal etc. etc. But if my friend is marrying this girl, she's probably not a wildebeest. Unless she's drugging me and sticking a broom handle up my ass, I'm not going to feel violated or assaulted. If you're capable of being the recipient of sexual advances from an attractive female, and you feel assaulted, then I don't even know what species you are!