Some people are drama crazed...they are bipolar, or have PTSD, or something, and they thrive on conflict / adrenalin and constant stimuli (usually negative).
All that can be done is to control how you respond to them, ideally by not responding ~ they won’t get the excitement and drama they crave and so they move on to get from some place else
I deal with this every day working with clients of DCYF, it used to be infuriating to me, but after all these years I now see it more as just sad really
Best of luck to you and your family, and hold on to the knowledge that eventually she won’t be a factor in you or your son's world after the kids are grown