Family Issues Support Group
Family issues is a huge range that go from minor conflict to major misbehaviour and even abuse on the part of individual members of the family occur. Whether you feel you are in a dysfunctional family or you're dealing with a very specific issue, this is the place to talk about it and find others who might be going through the same thing.

There is a really great and active board on here that's 'Caring for Aging Parents'
http://www.dailystrength.org/c/Caring-For-Aging-Parents/support-group
Often caregiving falls on one person much more than others.
They've also lived close by. You have no real idea of how much they have or haven't done for your mother over the years. "Holidays" that your mother gushed about, may have seemed more like chores that they conceded to. They may feel like it's your turn now. I really can't say.
My best advice is to decide what you can and can't manage, then work with local social services for getting the rest of the care your mother needs.
Downsizing too may be a better solution than you know.
My mother also has arthritis. She had her own house about four hours away from me. It was all getting to be too much. She resisted moving. She moved into a senior apartment (NOT assisted living). Since then, with the larger, flat indoor space to move around in...she's done very well. She's got activities and people that she talks to. Without everything being done for her, she still problem solves and stays sharp. She's 91 years old.
If your mom still has a house, I'd really really look into a senior apartment. I can't tell you how much my mother wished that she'd done it earlier. Her mental and physical health improved SO much as she moved around more. There's so much to be said about being independent too.
I think it will be easier on me having her here where I can help then worrying from afar that she's on her own in the apartment.
I just don't understand people who don't want to spend time with their aging parents ...
I used to go great lengths to drive to see my mother, and she'd stand in the driveway and tell the neighbors, in front of me, that I only came to see her "because she'd take me out to lunch". I didn't give a blank about the lunch. And I could buy one for the cost that it took to drive to see her...but...whatever. I'd take her on face value, and try to make her feel like I cared... Nope, that never worked. I don't think that I even knew that the feelings were dying, but I woke up one day and just didn't Feel anymore.
Like I said, I still see her. I still want her to be happy. I just get nothing out of the interaction. They say that the opposite of love is indifference...and that's what I feel... indifferent.
I don't know if that's what's happened with your siblings, but maybe it will help you understand them better.