This is such a yuck place to be. My family situation follows the same path. I'm the one tending to my dad, while my sister, who lives in another state lets me know I'm not doing things right. It wore me out. Then something odd happened. I looked back at the last 8 months, of what I accomplished, on what I did for my dad, and how I got my dad moved into a wonderful assisted living facility, and I cleared out his house. (He was a horder) and how I have set up his finances so he can live comfortably, and how I have a new relationship with my dad, and it's a happy one. Look to your accomplishments.
My sister doesn't help me or support me when it comes to my dad, and this won't change, but I'm not going to continue to dwell on this. I can't change her.
Another important part is I know that my immediate family, husband and two boys, were so important to helping with all this success. And I inturn had to realize that for a short time, 8 months, that things were crazy taking care of my dad, and moving him, etc, but I need to take care of me, and be with my husband,and kids, because that is giving me a balance. So I am at the point where I know dad's taken care of when I'm not there. And taking care of me - lets me truly enjoy my dad and our time together.