Jaffa cakes, I really feel for you in this situation.
The two older step children have obviously been exposed to emotional blackmail and seeing their mother “upset”, I really don’t know why women do this, men do it too, dignity just flies out of the window.
I am a bit concerned as to why your husband doesn’t have your back during all of this abuse. He doesn’t have to choose or be tied with loyalty, just stand back and take a view.
I speak from experience, my dad remarried when he was 35, he had three teenage daughters to bring up on his own. My stepmother did her best, although she was a little precious but hey ho that was her character, and many years ago. My dad was a single parent just as your husband’s ex is, but we always had to be respectful to our elders, no matter who they were. Too many people lack these basic manners these days.
Please do not tolerate this passive aggressive behaviour anymore, tell the daughter and your husband, and do it with a smile, maintain your dignity.
Do keep us posted, I wish you all the very best.x