Sounds like she's hecka threatened.
Not a nice thing to do, for sure.
Reminder that you guys don't need to have someone in your life that is making you feel uncomfortable like that or because you feel the responsibility to. It's nicer in the long run to end relationships like that, for all parties involved.
People in general have a bitchyness gene, not just girls but it does seem to come out more in triangle or small knit friend groups for sure.
I'd suggest not hitting her, as tempting as it may be