Ok,
i'm posting this here because i'm not sure wether i should tell this to my parents and sister.

Ok i'll start, i have a sister.
She is 20 years old and has a friend, all happy, just bought a home and plans of marriage.
He, my sisters's boyfriend is an alfa romeo freak and is active on a forums under the username of tinus313, so i wanted to check it out for once. not knowing the name of the site i typed "tinus313" into google.
But what i stumbled on, was his profile on sites looking for sex contacts, so i checked it out. on one of the sites his last visit was on september 19 2011 and hes been a member since 2007.
If id have to say thats after he met my sister..
and i checked the second one, ofcourse i knew it was him since it clearly was him on the picture, but whats worse is that the picture was one of him during a concert. i attended that concert and so did my parents, my sister and his parents. it hasn't been a long time since that concert.

Ok just asked my mother.. she was like why are you asking this, but nevermind.
the concert was in April/May one of those,
so he has been on that site, updating it while hes living together with my sister.
Btw, they started living together in february this year.

I think you people have an image of the problem now, i hope.
I don't want to ruin my sisters happiness, so i dont want her to find out.
But because i want her to be happy i actually want to tell her, because hes probably cheating on her.. he did this once before btw..
it was forgiven, but now this.
I'm seriously in a bind, i don't know wether to tell it or not.
If i tell my mother WWIII will commence, so..

I know im just rattling on and on, but its really hard on me...
Its not just about the relationship ending, but there's the money issue as well. what will happen with the house, the animals, the car, everything. And we already are people that arent swimming in money.

So i'm asking you all here on AnimeA for advice, i know there are some truly mature people on here which i hope can help me.
For the people who aren't going to take this seriously, fine by me.. but i'll probably get pissed at you.

Thanks in Advance~
Greetings Marc