Sounds like you've reached the "burn out" stage. I'm there as well, and it's tricky but you're going to have to stop identifying with your mom.
It's different caring for your own parents because "there one day goes I" kicks in. So watching them relays a message to your brain about what is up and coming in your own life. You'll change, and sometimes a lot. You'll irritate those around you, sometimes a lot. You'll be gross, sometimes really gross. lol
Since she had the stroke I wouldn't rule out a common dementia that follows strokes. My mother also had a stroke years ago, and also has dementia. My father had ALZ, but my moms is different and more eccentric. lol
Surgery, medicine, blood pressure can all cause mental issues and dementia. If she had mental issues to begin with as my mom did they just increase with age.
There is some great advice on here, and after applying it you will find some peace but I'm afraid the reality of your mom not thriving in older age will stick around. It has for me. I have to make an effort to live my life now and not look into the future as if my mom is a precursor of my own senior years. She's not. I could be completely different.
When people get older it's hard not to become bitchy when you lose the control of your own life that you once had. My mom would often make rude jokes about me being her maid, slave, etc. I finally realized it was due to her embarrassment of having to rely on others for dressing, grooming, toiletries, even the basics. It's why will all say we'd rather get struck by lighting instead of having a slow and steady decline of our facilities.
I can only offer understanding, and the advice others have given is great I'd use it. I don't think she's trying to **** you off, I think she's just pissed off. After all you have all your facilities, and she doesn't.
The eating disorder can be attributed to dementia. That's how my father passed, he starved himself to death and I was told this was a common way people die of dementia. The part of the brain that is hungry, knows not eating will kill you is slowly eaten away by the disease.
If she is depressed it might just be anorexia, which is also common in old age. Especially if she always felt good about her appearance and now feels ugly or not able to control her actions.
It's ok to be busy when you aren't really busy if you know what I mean. You sound like me and you might take on more than you have to. Only take on what you have to, you aren't a bad person if you let it go. Your dad married for better or worse. Kids don't need to feel that obligation. Just go to spend time, try to enjoy what's left of her, and live your own life while you can.
Happy feelings......!!!