Last week was my birthday and prom (My birthday fell on prom this year). I went in an amazing group of all of my best friends and I honestly had the night of my life. So a bit of back story, my friend K is not very well liked by my other best friends, but they tolerate her for my sake. K has said a few really shitty things in the past about my other friends and is generally intolerable in group settings, but she has helped me through some of the hardest times in my life. So... After prom I had my birthday party, it was fun and I could tell everyone but K was having a good time. See, K can only have a good time if the attention is centered on her... It's unfortunate. So another little factoid... K got a new boyfriend very recently and they are already boning like rabbits because he lives by himself. So lo and behold the night of my birthday party, she skips out when he leaves telling me that her mom wants her home (I knew she was lying). I asked her if she stayed over at L's house (L is her BF) and she admitted she did. No apology, nothing. She said "I knew you'd be pissed." But no sorry or anything. She doesn't understand why I'm mad though. I think I need to end this friendship because of multiple reasons but... Am I really doing the right thing? Can anyone give me advice?