a girl you're with should never whip out her tits to another guy unless she's a stripper and you know or you're with her and you egg her on or something.
my mom and grandmother did shit like that. i was humiliated. i was a child and couldnt do anything about it. i have always sworn that if my wife starts that shit.....well she had better not even try it. dont get me started.
she has been trying to make it up to me so hard since the incident. buying me dinner and giving me blowjobs left and right. I think im gonna dump her though.
did she tell you or did you find out from someone else?
if it's the later, you need to dump her yesterday.
if it's the first, it's a judgement call. if she's a chick you're just seeing and you use her as a cumdumpster, no sweat. if she's really your girl, then that's unacceptable and a sign of bad things to come.