Hello, I Am A 64 Yr Old Widow Who Is

Hello, I am a 64 yr old widow who is sole caregiver for my mother. My father died 4 yrs ago and my mother has some dementia and inability to remember past events accurately. While she is in independent living within a group retirement community, I still need to take care of her finances, groceries, doctors, and personal business. She is 92 yrs. old and physically doing well; however, her mental state is declining. I am struggling with depression which I have never had previously. Could this depression be a result of taking care of my mother and watching her decline? I don't want to sound selfish or self centered, but I sometimes feel I am getting a view of my future and that is depressing. Just searching for some insight please. Thank you for any advise you can offer.