Dear Annie: I have known one of my friends, “Pam,” for more than 50 years, and at times she has been a very good friend. She and her husband introduced me to my now-ex-husband and were both in my wedding party. Last year, I had a disagreement with a mutual friend, “Sharon.” Quite frankly, I thought Sharon was in the wrong, but I decided her friendship was more important than who was right and…