I and my husband have living with and taking care of my mother with dementia for over 5 years. It has gotten to the point where we konw we cannot offer her the type of care she needs and still care for ourselves, make a living and save for our own retirement. Out ability to work (we are self employed) has been deeply affected) and we can no longer do this to ourselves.
She is in her own world and comfortable in her home, but we are have not been able to take time off at all in those years. Although she has asked to go to a nursing home, now that it is a reality, she does not want to go.
We have a heart an do love her, but we are doing a dis-service to our own life and her ability to have better care as well.
Focus on that. It may not register with your mom - but if it were me, and I was there at one point - but I would want to pay her the respect of at least being honest with her. The fact of the matter is that your mother needs more - and better care than you can provide. It's not a criticism- you and hubby are not medically trained and able to look after her needs round the clock. Tell mom that and go from there.
I know when I faced my mother wanting to move in with me it was impossible to even consider in a dozen different ways. But for my mom I needed to make it all about her - which all the other reasons were as well but was not as clear for her to see. Having mom live in our basement because we only have a two bedroom house - occupied by hubby and me and our sevearly disabled son - well, that didn't cut it for my mom - she insisted she'd be just fine living alone in our basement- with me running up and down the stairs all day - looking after her and taking care of my son. There is no reasoning with dementia! So I stuck with the obvious truth - my mom needed more - and better care, than I could provide. Period.
Give it a shot. Good luck to you - it's definitely a tough spot to be in right now. But it will pass and everyone will adjust to a "new normal" once the move is made.
My mother is like a badger -- a social phobic one. If your mother is not so stubborn, it might be easier for you. Some of the facilities are very nice and have games and activities for residents. It could be that your mother would actually enjoy them after a month or two. She might discover she loves bingo or some other activity and it will make all the difference.
There is no easy way to tell them. The only thing to remember is that we live a minute at a time. When you tell her, it will be tough. Moving her into her new place will be difficult. But when it's done, the time will be over and you can know that it was the best thing for everyone. You just have to get through the rough patch to get to the other side.