Hi 7885,
I'd like to welcome you to bpdfamily. I completely understand how frustrating it is when we get blamed for everything. BPD is a persecution complex, a pwBPD believes that their circumstances are not caused by themselves, it's caused externally by others. She'll blame you or say that you're not a good dad because she's saving the kids and casting as persecutor and the kids are victims, that validates that she's a good mother to her. A pwBPD have dependency issues and rely on others to do things that an adult should really be doing themselves, if you're divorced you're not obligated, you didn't leave what types of things that she's asking of you but if it's for the kids, i'd do it for them and i'm sure that you would too.
It helps to share what you're going through with people that have walked a mile in your shoes, you're not alone.