Hi Deb, welcome to the board. I totally sympathize with everything you're saying. My "ditzy" and over emotional mom suddenly started repeating the same words and sentences over and over when my 3rd son was 3 weeks old. And then I noticed she could barely lift her feet or cut her food. A month later she was diagnosed with Parkinson's and a couple months after that a dementia diagnosis. By the time my son was 6 months old my 69 yr. old mom was in assisted living. I have no siblings and my father passed away 15 years ago, so it's all been up to me to navigate these waters.
I'm 36 now and she's 72, and after plateauing for a while, she's declining quickly again. You just have to deal with each challenge as it comes. There are no "right" answers to a lot of these challenges. Just get help when you need it! If I had not acted quickly and found my mom a safe place to live I don't think she'd be alive. And I knew I wasn't equipped to handle her at all. I do battle feelings of guilt, but it's really lessening now as I slowly realize how truly helpless we all are in fighting this disease. Just trust your instincts, you're making all the right decisions.
For the first 25 years or so of my life my mom had untreated mental illness, which robbed a lot of enjoyable time I could have spent with her. When she finally sought treatment she was like the mom I never had, and within a handful of years she slipped away again to dementia. I totally understand your feelings of loss. Please keep participating on this board, everyone is SO understanding and helpful. Support is essential, however you can get it!