I know exactly what you are saying. I am also a caregiver of my mother who lives with me and my family. She is dying of lung cancer and probably near the end now. I am totally exhausted all the time and have interest in pretty much NOTHING at this point. Some days I wonder how I will get through another ...... and then I remember.....by the grace of GOD.
Hang in there and just try to take one day...or one hour...at a time.