Re: i HATE my stepsons bio mom!
I can't speak from personal experience. But my mother's good friend went through this with her nieces 20+ years ago, and she was sharing the story with us over the summer. Their mother ran off on their dad and the 2 girls when they were 3 and 5. The dad was totally overwhelmed and not in a good place, and so his brother and sister-in-law adopted the girls. Basically, same song-and-dance you describe- she'd call, make promises that didn't happen...aunt/mom described it as "things would just be starting to go well, and then she'd call and the get the girls all stirred up with lies."
Anyway, I'm just posting here to say, I know that auntie/mama had a tough time with both girls, the one even into her teens. But now they're adults, married and having their own families, and who do you think gets called "grandma"? It's the woman who raised them and was there to be honest with them, care for them, and tuck them in. All to say, *hugs* to you. It's hard in the moment, but as time goes on, kids know who cared for them, and in the long run you being the parent will be more important to him than her lies and shenanigans.
Kara, engaged to B, mama to Jaime Gabriel 04/09 and Beatriz Xochitll 10/12