Best friend cheated

So guys I think it’s all about to kick off and I need your advice!!

My bestie cheated on her boyfriend with her ex. (I was with her at the time) and we all promised not to tell anyone about it. I’m friends with her boyfriend as well so it’s a very sticky situation.

I accidentally told one of my mates about it because it angered me and I had to get it out. My mate said he wouldn’t say anything to anyone.

I just had a message from one of my other friends saying ‘I’ve heard rumours that **** cheated on her boyfriend’ now I’m panicking because if it gets out it’ll probably be all my fault and she’s gonna hate me 😭😭I don’t wanna fall out over this but she shouldn’t of done it in the first place so I’m really really guilty now