Friend advice!

Ok so one of my close friends told my best friend that a girl spread a rumor abt her “sucking dick” all the time. Obviously this isn’t true. But this just sparked so much drama. The girl that spread the rumor is now telling my best friend that I talked shit about her (which I admit was true but it was a long time ago) and I’m scared that when the two of them talk, the girl that spread the rumor abt my best friend will tell her that I gossiped abt her a long time ago. I don’t know what to do, I know it was wrong but I just don’t want her to know and I’m scared Bc I love her so much and she’s my only friend. When the two of them talked, she already started telling my bff that I said smthn abt her a long time ago and I told her it wasn’t true Bc I was too scared pls tell me what I should do