Bestgayle

Your supportive female friend whose always been there for you. Surpassing all your exceptions as a friend or your sister. She loves you so much that one would think you in a lesbian relationship. Her children are your godchildren.
The etymology of the word emerges from the flourishing relationship between Oprah Winfrey and her best-friend Gayle King.

Gayle is Oprahs bestgayle.
Friend I love you, you my bestgayle.