Hi Kelly,
I just wanted to chime in with this tiny bit. Even if you found a job that was better than your current job with your Nmom, separating from her would be hard. Going through the process of letting go (of soooo many things, like hopes that things will get better), is very hard. But it has to be done.
I hear you thinking about your kids and trying to make sound financial plans regarding their education, but what about the example you're setting for them? What are you teaching them by continuing to work with your Nmom?
And what about you? As you said, you've been reading about all these aging Nmoms (oh, and I'm convinced they'll outlive us all for sheer stubbornness

I've got a grandNmom proving my point as we speak), and you're worried that you'll be old yourself by the time you receive the inheritance. But just consider this. What's more important, money or knowing who you are?
Being around an N sucks the life out of you, the YOU out of you. When you're beginning to learn about the effects of an N, it can be so disorienting and scary - and I know some who'd sometimes rather go back to the comfort of where things were before because it's what they know. How much harder will this be if you're still interacting with your Nmom every day of the week?
So what's more important? A job that fits your shedule and income requirements, or setting a good example for your children by finding the courage to find yourself?
If your husband really wants you to be happy, then he'll understand that the path to your happiness (and ultimately your happiness together) depends on you finding your way through some tough times ahead.
But as tough as this process may be, there are so many here to help you through the rough patches.

Best wishes,
Wildflower