What would you do if you were in my shoes?

Well first of all, kudos to you for taking some much needed time to rest... and has been said many times on this sight, guilt is part of caregiving.....
It's not that you weren't 'strong' enough to keep doing this job, it's the fact that you are human and can only endure so much physically,mentally and spiritually before we hit bottom....You ARE strong, that's why you were able to go past what others could have done.... You ARE entitled to have a break, you ARE in need of rest and recoup time.... if you are not ready to have her back, then that is part of the consequences our elders have to endure for not wanting to go to AL or NH's.... it is not punishment for them, it is a break we HAVE to have in order to give them any kind of quality care....
At some point we have to let go of the end result... let things happen as they are intended to happen.... we all do this... push past our endurance and then feel guilty.... that's why we were chosen for the job... because we can and we do do it..... so when we are blessed with time out.... we fret away our resting time by worrying... we have been moved out of our 'comfort zone' and are not sure how to 'be' anymore with out the constant call of caregiving ringing in our heads....it took you a long time to get where you are, it's not going away with a little rest.... it's like we are soldiers, we have a routine, we pretty much what comes next from minute to minute... then.......... we are thrown into 'civilian' life and don't have a clue how other people live anymore....
So with all that being said, you have answered your own question... you are not ready to get back in the trenches yet... if ever... that decision will be made somewhere down the line..... try not to focus on the unknown future and relearn how to be YOU.....

You will be ok... she will be ok.... maybe things aren't as you would like them, but they are what they are.... and taking her back before you have regained your 'footing' so to speak, is not only unhealthy but dangerous for you both.... so take a deep breath, tell yourself you have a heart of gold, you deserve some respite, and try to stay in 'here and now'.... this minute is all you have..... prayers and thoughts for you today.... take care of you...... we are all here for you....hugs across the miles...

Don't try to do something you know you can't do. Don't go back to the same schedule and the same demands as before or you will go back to the same result. Unless something can be done differently - like a lot more respite built in, a day program for Mom, home health aides, or maybe the need it for some major change in the way you do things or look at things, SOMETHING that reduces the burden, you won't last another 12 years or even another 12 months. I wish it were easier, that siblings would see the choice to let you burn out and have mom end up passed around to relatives or in assissted living versus step up and pitch in, or that any of us could give it our best without feeling guilty when that's just not enough...God bless you whatever you decide to do!