I think assisted living is probably a good idea they are equipped to handle older adults and keep them safe. Also they are made for carts or wheel chairs. Have elevators, then folks her own age and activities geared to them. I'd say pick 5 of them that you think are good and say mum I know you are unhappy probably lonely and bored these are five places you can live that will be better so what say we shop and you pick the one you like best.
If you come with your feelings of unhappiness she'll take it personal and make you feel guilty or at least attempt it. She'll be safer there anyway and you will not have to worry about her blowing up the kitchen or taking her to doctor's visits and most of them are pretty sharp eyed about things.
They have pendants to active if they fall and pull chains in the bathroom they make attempts to keep people from falling or being hurt if they are any good. I'd say pick one that is clean and the food is good also check the bathrooms and ask to see a unit if you can. From what you described I see assisted living as the best option yet she is not going to make it easy to get her out of your house because of the contrary nature of the complaints it's like she wants attention and is using emotional tug of war to get it.
However you say your needs or wants she ain't going to listen. If that's how your relationship has always been then trust me honey she ain't gonna listen. My parents don't listen either and I hear it when I read your words.
Are you tired after talking or interacting with her?
Do you have an emotional reaction when she complains like angry or immediately react with some emotion or the other?
Be honest are you sometimes frustrated with her or your situation?
Has this been the case through out most of your life?
Whose idea was it for her to live with you? Did she put pressure or make you feel guilty and are the people in your house who live there fed up with her?
Did she object to you finding your own life?
Did she always complain in the manner you described just now?
If any of these or most of them are true then she's going to give you a bunch of trouble. You are going to need your family to help you deal with her countermove you can bet she'll make one because the truth is I think she enjoys complaining and making you feel guilty about doing what you need or want. This is why she doesn't want you to expand the apartment or to go out and complains when you do it makes her feel in control and she's not going to cooperate unless you pick five and let her pick one.
The complaining is not about her being unhappy in the way you described it but about making you feel inadequate since if she always does this then she must be getting something out of it and you gotta ask yourself what it is? What's more likely given your relationship throughout your life not just this time in her life?
If you think about it then you'll find out why you are miserable and lost. Regardless of your decision what comes first is learning what her game is and refusing to play it her way any longer. You are too emotionally involved in this to come in stating what your needs are tell her what you've observed from the situation at hand it will look like concern yet before you talk about it bring the data in on the assisted care facillities the five of them you inspected and place the data before her and present it just like I recommended you do and then take her to all of them let her rest and then she picks the one she likes the best.
Once you get her out then you can clean that apartment up and rent it to someone to defray some of the expenses. Find out what you can get through a service since they probably screen the people they place so you don't end up with a total loser or something. Who could be worse than your mom trust me there are some real turkey's out there.
Whatever you do she's going to try what worked when you were a kid most likely and what worked most of your life and she might even cry or accuse you of everything she can think of. I believe you should role play the interaction with a friend and tell the friend to throw everything she could think of including tears, accusations that you are a terrible daughter, call you names and do the anger thing or the we're a family and we should help each other and anything make it as hard as can be managed to stand your ground and then switch roles to show her more what your mom does to pressure you into something so she can gear her attacks and such in that direction.
Also I recommend reading verbal self-defense, it's a book and it will help with other things not just this situation it's useful. Also William Ury's Getting past no. This is tough stuff it's alot like a math test or an English exam you would not think of walking into one of them without studying.
So be prepared for a serious back lash yet don't do the victim number either or she is not going to respect you. Don't get angry either. Expect the counter move. So pick a role play partner who is really good at turning the screws and is really agressive also doesn't pull punches either and practice until nothing gets you to emotionally react suddenly no matter what gets said. She's going to try to push your buttons just expect it she's done so probably all your life that's why this is wearing you down so much.
If you expect to be hit or attacked then you won't be angry or surprised when it does and you can think about how to deal with it best and in the most effective manner you can think of.
This will help you in every area of your life. Clear and calm reasoning under extreme pressure. It will help you buy and sell stuff without getting taken for a fool, it will help you deal with kids, husbands, bosses, coworkers, business partners tricky customers and anyone else. Prepare for the counter move imagine her worst reaction what's the worst thing you think she will do and what she is likely to and make up dialog then step away calm down and then work on defusing it even if you do not have a partner you got a computer or a notebook.
Imagine yourself in her situation add how she typically reacts to anything she doesn't like and what her methods are and then think how she would use them to get her way. Go over your interaction history for clues. You know your mom pretty well you've known her all your life.
Depression isn't the only thing that's going on in this mix. I'm right aren't I? Don't go off on her she probably doesn't know how else to relate and you've gotta learn how to move differently as well. My guess is this has beeen going on a long time. Get counselling as well. Good luck.