My mom has always been very independent and done as she pleased, also very demanding. She wants me and my brother around all the time feels alone in the assisted living because we’re not there. She can’t see to read anymore is bored and very depressed. It is so frustrating she feels sorry for herself every hour of everyday. I feel so guilty always.
You can't 'fix' this. There's no cure for 95, I'm afraid. Taking her to live with you is a gigantic mistake, as you probably already know, so don't even consider it. You and your brother can visit her as time permits, and even take her out to dinner if she's interested in going, but then you can go home afterward.
Keep it that way, for your own sanity!
Also, with progression, their ability to read my decline, which you mention, as well as their ability to engage in conversation with other residents or to participate in activities. In a regular AL, my LO was lost due to her progression. I don't see it as feeling sorry for yourself, but, being terrified and uncomfortable. I might discuss things with the staff to see if she unable to fit in now. I know that my LO's progression prevented her from doing that. Her needs became too much and I moved her to a Memory Care unit. That was a huge improvement and she seemed much more content there, since there was more hands on care. And, the activities were more on her level. I saw a big change with the medication to help her mood and the increased care.
Guilt is a self imposed emotion, that is keeping you stuck. Life is not perfect, accept that, it is not your job to make her happy...won't work anyway...happiness is an inside job.
All of those will still be true no matter where your mother is, or (come to that) who is in the room with her.
It is not unnatural, though, that her main source of consolation is her children. You do tend to focus on what really, really matters to you when you're losing everything, after all, don't you.
That does not mean that you and your brother should upend your entire lives to spend every spare moment keeping your mother's misery company - even if it weren't an unreasonable demand, it wouldn't make enough difference to your mother to be worth the sacrifice.
But do recognise how important your presence is to her, and give her what time you can. You can't solve her difficulties but you yourself are a comfort to her.