Welcome!
We're glad you found your way to us, although the reason is not pleasant, to say the least. There are quite a few stepmother and step-grandmother on this board who have found themselves in similar situations. We "get it."
I am married to a man who had a previous marriage of 33 years (the past 14 years living separately) with a woman who is undiagnosed BPD/NPD. H and I had known each other as teens and reconnected in 2005, were married within months. He did not have a name for his ex's behavior until I talked with him about BPD or NPD. H was deep into FOG (Fear-Obligation-Guilt), was enabling, and had CPTSD. It was rough. His adult children had all begged him to divorce from the time they were in their teens.
I had no idea what I was walking into.
With much work around boundaries and much love, we have reached a point where Ex rarely affects us or our household. This was necessary because of multiple, intrusive actions in the first few years. Their adult children are coping much better than they were 10 years ago, but there are still situations that arise resulting in conflict (primarily between the Ex and the two daighters). There are two granddaughters -- one is only 3, the other is 18 and has been aware of her grandmother's problems since about age 11-12.
Our guideline now is that Ex only texts or calls H on his cell phone if there is something critical going on with the adult children or grandchildren -- and he takes the call in another room or outside. Nothing has qualified as critical in a long time. She no longer calls the house phone (we retired and moved, so she doesn't even have that number.) That was a problem early on, and she abused it. We were getting frantic, hysterical, or raging calls far too often.
What situations are causing you the most stress right now?
What is your husband's attitude about his exes? Is H also frustrated at their access to him?