Someone PLEASE explain this to me???? (As no therapists have done so...)

Okay...I am male, and I have a very strange, mean stepmother to put it nicely.

She has ALWAYS been jealous of the females I dated!!! Always!!! I mean enviously jealous!!! Now...get this...when I break up with any female...she "instantly" is their best friend and runs to them to gossip about me behind my back!!

This wicked woman married my father (RIP) and...she would NOT even attend his funeral!!! Since then, I have pretty much broken it off with her, I can handle her disrespecting me...but not my father!!!!!...but still. I would like some explanations/opinions please???