Up to what extent do we need to help a sister?

Wow what do you mean left? This isn't your place to raise the children she gave birth to and they are probably monsters because she isn't there. You should be able to live your own life because it is only fair. This is her life she chose to have those children and she needs to be responsible for them and not strictly financially. You should also not have guilt about living your own life and it seems like you do. I feel bad for the kids, but it's not your place. My sister watches my kids for me while I am at work and I pay her to do so. She would do it for free but I don't think that is fair to ask of her so it is her job to watch them and I am home everyday around the same time. Family helps family and I am always for that but it seems like she is taking advantage of you now and that I hate. So I think you've extended as much as you need to. I mean seriously she can't find a job closer to her kids?