Also I should note that I am a covert so this was ALL so new and foreign to me. I would cry and stress over this. So I hope this gives you some relief.
Your husband's ex-wife sounds like a nut case. At least on this topic. In these situations, I can't repeat myself enough times
So I think the best strategy to handling this emotionally is to quietly acknowledge she's a nut case and ignore anything she has to say on the matter. Frankly, your stake president should have told you the same thing*.
* While it may be true that, given decades (centuries?) you may come to like her, that notion is immaterial to your sealing.
