this girl is insufferable and idk what to do

Me and this girl, well call her sara, were talking for a few months and then i eventually asked her out. We dated for a few weeks before i realized that shes actually js an insufferable person. My mental health isnt great rn so i broke up with her bc i felt like i couldnt be in a healthh relationship with my mental health so bad. It was fine and we were still on good terms but she still acts like were dating and stuff. She even tells people were still dating. I even talked to her A SECOND TIME abt how i dont want a relationship or anything rn. AND SHE STILL ACTS LIKE WERE DATING. She vents to me at least TWICE a day EVERY SINGLE DAY and i feel like i cant help her, and when i try to comfort her she says its not helping. I cant have someone vent to me every day but i cant tell her to stop because half the time she vents to me saying stuff like "oh im scared tou dont like me anymore" like yeah i js broke up with u. And shes gonna get everyone to hate me and all of our friends to hate me if i say anything. 💀