I hate to say it, but having been that age myself not that long ago, you just need to let it pass. I am 25 with my first child and I know I will face that eventually but I was the same way. It's not that we hate you or anything it's that we are just gaining a sense of independence and don't want anyone to tell us that we are wrong nor try to take it away from us. I now wish I could take back the way I acted but hind sight is 20/20. I know you are feeling a bit helpless but in my opinion the best thing my mother did for me was be there when I needed her and let me be when I was not being the nicest. She is my best friend now, next to my husband that is. Just try to give it some time and it will pass.
Plus I don't agree with the tough love theory. My husbands parents did that to him and all it did was drive him away. So whatever you do try not to do that. My husband is 30 and still holds some resentment for his parents and the way they handled things as he was growing up. I really don't think you want her to resent you. Plus at that age, they are a bit over dramatic, so if you cut them off she may feel like you hate her and it may push her away even more.