I know how you feel. My mom was diagnosed with ALS in June 09' (first symptom in left hand- late March 09') By the end of June she couldn't use her arms, by end of August she couldn't walk, by Novemeber eating was very difficult...she passed in January 10'. She battled for 10 months. I was her only primary care giver. I had some help from hospice volunteers to give me a couple hours break here and there. I would leave her to work a few hours and come home...eventually having to take a leave of absence. I left my husband and kids to live with her and care for her.
I WOULD DO IT ALL OVER AGAIN! It was the hardest most difficult time of my life. I was incredibly strong because I had to be. For me, there wasn't a choice. It was my mom...my best friend. She didn't ask for this horrible disease. I was wiped out caring for her (physically and emotionally). I have MS and my disease has flared since all of the wear and stress. Again, I would do it again.
You are doing all the right things...getting support and familiarizing yourself with disease (It's scary to read but it helps you stay one step ahead). You prepare yourself to help your love one get through unexpected situations.
I wish you and your family the very best. I hope you all will find your way. I find myself visiting this site even after my mom's passing...because I know how difficult it is and how it helps to know that there are people out there that have been in your very shoes.