I can't back my friend up on this

My friend got in a fight at school (kinda). This is just what I've been told, I was not there but my friend who got into the fight told me and some other friends this and she sounded like proud of herself(?) I'm going to write what she told us, how she told it to us.

"During class I got into a fight with (name), I took her waterbottle from her and was sort of tossing it between my hands and she told me to give it back but me being me, I didn't because that's just how I am. Then she like grabbed my shoulder and told me to give it back so I grabbed the back of her neck like hard and threw her on the ground, and I kept pounding her in the face, she shouldn't have touched me and it wouldn't have happened"

I wish I was joking when I'm telling you that's what she said, two of my friends like thought she was in the right while me and another friend just thought that was crazy. I get not wanting to be touched but you could tell her that instead of beating her up, and the reason for taking her waterbottle is fucking insane, maybe you should've just given it back, and she sounded like she failed to see why she was getting in trouble? Like I told her that I can't back her up on this because it's fucking crazy, and now I'm a bit afraid of her, a part of me is just wishing she was being hyperbolic in some way and that girl didn't get that hurt. I checked with my friend to see if she was some asshole who deserved it but no, she didn't even do anything to her except grab my friends shoulder to get something back. Anyways, I can't back my friend up on that because that's fucking crazy.

XOXO, Hazelle K.