<human>: So my girlfriend of a year wanted to go hang out with her and her girlfriend and invited me. I calmly and politely declined the offer in the nicest way possible because I didn't want to look like the bad guy. I hate her friend, I know she talks trash about me. I just know it. What my girlfriend responds about those remarks I'm not sure. Anyways, she started getting all offensive because she knows I don't like her and I don't want to surround myself with negative vibes. I'm sure nobody wants to be around people who rub them the wrong way. Anyways, I just need help on this situation because she always gets mad at me over it. How do I tell her that I don't ever want to hang around her friend without starting a fight.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: I get along with everyone of her friends besides this one. And she makes a big deal about it and they've only been friends for a month.