Personal attacks, rather than trying to support your point of view with facts, are a very immature way to argue and usually come out when the person either has no grounds to support his/her argument or knows they are in the wrong & are just trying to come out of the conversation on top any way they can.
As for being upset, of course I would be! You have to wonder where that comment came from; I mean, was she thinking that the whole time you've known her and it is only coming out now because she's angry with you? Maybe there is some jealousy there or maybe she was just trying to hurt you more b/c you were hurting her w/what you were saying at the time or maybe she was tripping off somebody else when you two got into it...But no matter the reason, that is a very hurtful thing to say and you guys are going to need to clear the air.
at 9:51 AM on Aug. 17, 2009