Wow! I think you are blessed! Rarely does a person have four friends that they can feel safe in telling them anything. Many of us have friends who would probably help us out. And few of us have friends we can call just to talk - most people want to know why we are calling. Count your blessings because you have four great ones in my opinion!
While I have 7 good friends that I can think of, both male and female, my best friend will always be my wife. However, I am also thankful for the friends that I have who have kept in touch with me throughout my life and after retirement. We care about each other and that's so important nowadays, especially when families are so fractured now that you can't even count on them.
Very rare and huge gift to have that many good friends. I really believe the #1 factor for quality of life, is the quality of friends. With all of your caregiving demands ( past and present ), that is especially true.