How to detach from suspected covert without triggering the rage/smear campaign

Unfortunately this is not my first rodeo. Kind of disappointed in myself for falling into this trap again. Last time I simply didn't care about their reaction because I was at a point where I didn't care about everything in my life burning down. This one... I really cant afford to burn down my life for. I think grey rocking is the way to go, but I could do with some tips. People assume we are best friends, I get asked about them all the time as if we are a pair... how do I deflect talking about them without provoking a level surprise and curiosity in people that they then might go on to talk about and word might get back to them. I'm not a good liar so I can't fake that we are ok.