so you are a single mom

She was also in crippling debt and suffered from depression - something you wouldn't know if you didn't read the book. (And something that would've made her decision a little more understandable)

In her eyes she was a failure as a mother -especially after the Krissy thing.

She thought that her children would have a better chance at life being raised by her sister - she thought they needed the money more than they needed their mother.

And as long as she was alive Runner would always swoop in and make a mess out of their lives.

I think it might have worked better if the mother had seemed more unhinged. She just seemed fatigued, not actually disturbed. It's a crazy plan, so she should have been more frayed and teetering on the edge of madness imo. Instead it's like she was a good and loving mother who was just having a very hard time.

When she speaks to her sister about the idea of leaving her kids with her, there's no trace of awareness that this would be a horrible thing to do to the kids or a major burden for her sister. It seems less like she's desperate than that she's just really dumb.