SUBREDDIT: r/relationships
TITLE: My [21m] girlfriend [21f] talks negatively of my friends and family
POST: I've been dating this girl for about 3 months and we've now been living together for about a month. I'm really crazy about this girl, but we got into an argument today. 

We were having just another normal conversation, talking about my dad, when she replied "fuck him" about some advice he gave me on the phone regarding having a serious relationship at this age. 

I wasn't necessarily mad about what she had said, I think it was justified, but it brought back a flood of all the negative things she has said about my friends and family since I met her, and I stormed out of the house in anger. In all the times she has been around me i havent once heard her say anything positive about my friends or family. I later wrote her a short paragraph about how that made me feel and why I became so angry and gave it to her in person. She read through it and all she had to say was "Oh, sorry. That's a fatal flaw of mine." I don't feel I have closure from that... it wasn't a real apology. 

Am I justified in this thinking? How do I continue from here? Thank you!
TL;DR: 
Girlfriend talked a lot of mess about my family and friends, didn't give a good apology, expects everything to be normal. How do I continue from here?