Is there anything i can do?

I fear i am losing my best friend. She just finished her freshman year in college and came home and is completely different. Last time i saw her on her spring break she was still the same girl i knew. Since high school she has beens friends with a girl i cant stand. my friend and this girl call each other every night at 11:05 on the dot. If my friend is five minutes late the other girl gets angry. If my friend tells the other girl that she was invited to go hang out with some of her other friends, the girl gets angry and tells her "if you go then you will atop texting me and wont talk to me and thats not fair to me." i have personally heard this girl tell my friend this. My friends parents dont like how this girl treats my friend and neither does a number of our close friends. My friend is now saying thay she has felt like we have been growing apart for a few weeks now. She is suddenly not responding to my texts and not talking to me and another friend and telling us that we never try to keep in touch with her and nevef try and hang out with her. I send her a mass email eaxh week with updates from here and asking a bunch of questions about how she and school is going. Each time we found out she was coming home we tried to set up a girls night so we could all hang out as a group. Sometimes she would say no cause she had plans with the boyfriend or family or other friends and we told her we would try again another time. She is my best friend my maid of honor for my wedding in november and is like my sister. We have been through so much together. I am scared i may be losing my best friend and i dont know what to do anymore. Someone please help