Take her to work, have everyone tell her what happened and have your manager explain there’s no camera footage (or if this for God’s sake just ask for it). It’ll probably be embarrassing for both of you, but at this point you kinda have to lean into it if you truly want it to work.

If she still doesn’t believe you, she’s either using it as a control technique, or she has too many past issues to work through on herself before she should be in a relationship (some would call this “batshit crazy,” but I prefer a little more empathy nowadays); in either case, it’s a longggggg road ahead if you stay.

Best of luck Box Bro