You poor poor pet.
I'm so sorry that life has been so hard.
But you are so resilient to have come so far.
You can get through this too, but you have to put your needs first.
It is amazing how selfish women like your mother so conveniently play victim in relationships when it suits them.
You were a defenseless child and the only person she concerned herself about, is herself.
Well now it is your turn to finally put yours first.
In this instance, you have to do it, to protect YOUR children.
Do not allow yourself to be used at this point.
Your sister is correct in putting up boundaries.
Your gut is trying to protect you, please listen to this.
Your mother has moved near you, to use you.
It is not about adding anything to your life, or the lives of your children.
She chose herself above you many, many times.
Now you need to do the same.
There is a suggestion of inappropriate behaviour on the part of your awful step father in your last post.
If this is true, its even worse.
Please stop thinking of others and start by being to yourself, to the little child you were, that was so poorly treated.
That little girl should be your only priority.
Leave your mother to get on with her life, users like her will always find someone else to use.