Oh Teresa. I'm so sorry

What a difficult situation. Try to not be so hard on yourself. You are a good friend. You were thinking of her and praying for her and she has lots of family around to comfort her. She knows she was in your thoughts if not there physically.Try and remember the happy memories of her and your good times together when she was in good health.
When this is all over maybe you can do something for cancer in her memory.
Don't Feel Guilty!!!!!!! You did your very best. You are buring the candle at both ends eight now. Caregiving is the hardest job in the world.