Total NC by you and your new partner with both ex.'s.
Stay away from "fake book".
lovenature has a good point here. I'm a believer in 'what I don't know can't hurt me'. As someone (rare I know) who opts out of SM, my choice to do so is so that I can't be influenced or affected in the way that you describe. In short, it's up to others what they think of us and say about that privately or publicly. We can choose not to make it our business.
If that were to affect something directly like causing issues in your career, you would have grounds to raise these issues with the authorities.
Have the activities of these individuals been damaging to you?
Love and light x
