Don't know if I can do this again

In the last four years, my father has had cancer of the throat, twice, the last one resulting In the loss of his voice box. During this time, his wife and my stepmom developed lung cancer. As was their wishes, we didn't talk much about it, but there were many nights in the ER, appointments, and my father who has always been narcissistic, didn't seem to notice how ill his wife was. Stepmom lived an extremely unpleasant year after diagnosis, and since there was no discussion, the financial and legal issues after her passing were huge, requiring hours and hours of work, as Dad paid no attention. Dad also couldn't live on his own anymore, so we found him a beautiful place in a retirement/assisted living facility. During this time, and to a lesser degree before, Dad is incredibly abusive verbally. We are in the process of trying to sell his house.

A few months ago, Dad had a tumor in his lung, had cyber knife surgery, which was effective on that tumor, but now there is another in the same lung, and a suspicious area in his other lung. He is starting chemo on Monday. So, with this as a background, I don't really know how much more I can take. I have given it to God, but in the midst of the unhappiness, we have had great joy, and that is what I focus on.

My issue is that I own a one person business that has suffered greatly, and I am very scared that I will lose my business if I don't give it attention, but know that my Dad is going to be miserable (he has never has chemo before, just radiation and surgery). I don't know how to balance it all. I feel selfish, and alone in this, and angry, and resentful. My husband also owns a business, and everything is run out of our house. I am not sleeping.

I just don't know what to do any more.