How to deal with toxic lying coworker?

I’ll say it right off the bat- we do not have HR, flat structure blah blah blah. One of my teammates being extremely toxic going behind my back and spinning lies to get her way. To the point she started logging screenshots in jira with my messages from slack ripped out of context. Thankfully I caught that task and provided screenshots of full conversation but it feels so excessive and childish. We are all adults what kind of high school drama is this? My next step would be going directly to COO and I’m not sure I want to involve c-suite person here… #officelife #culture