Well i was going out with this girl i realy like for 7 years and so my sister was a lesbian and i was ok wth it i didnt realy care but a week ago when i came back from skateboarding i found my sister having sex with my gf and i was shocked as hell so i dumped my gf but now my gf and my sister are dating and its anyoing hearing my sister dating my ex (btw i nevr even knew my gf was bi)

Fuck that. I'd have stayed with her. So what she fucked your sister. If I broke up with every girl that fucked my sister. I'd have never broke up with anyone, but that still is stupid.