How do I stop suddenly burning bridges with people?

I keep cutting ties with people, those who wronged me and treated me well all the same. A mutual friend of mine and my ex always asks why we aren't in contact anymore and I don't quite know myself. I would say we were on good terms but they brought up bad feelings. The moment I feel discomfort I haul ass for the exit and I can't stand another moment of the guilt that comes with it. I feel like a bad person but I can't stop this awful habit no matter how hard I try. Any ways to kick it?