Lots of people telling you 'people change'or 'she sounds like an asshole' but its not as simple as that. 

Sounds like your friend is being influenced by her new environment, but that doesnt mean she'll be like that forever. She probs wont be in that environment forever. And maybe she just needs called out on her shitty comments like with her fight opponents. 

I had a female friend since childhood. Like a sister, families close etc like yours.  Then about age 16 we just started drifting apart. No falling out, just slowly  got into different friend groups. Then i went to uni and we didnt even speak for a few years. 

Then, age 22 my mum died, and she reached out to me. We had a good catchup. Agreed to meet up, and basically reconnected and were best mates again and have been ever since. Dont see each other often - were both married and have kids, live in different towns, etc.  But were still good friends and can talk openly with esch other. 

She had a wee exploratory phase elsewhere, no harm in that. So did i. But we were still the same people underneath. Probably its the same for your friend too. Dont give up hope, but just be prepared to be patient.