Dear Mary: How should I handle my bitchy friend’s birthday cards?

Q. Many years ago I was asked to officiate at a funeral for a family I did not know. As far as I was concerned the service went neither better nor worse than any other and afterwards I went along to what the undertaker used to call ‘the bunfight’ at the local pub. The mourners were facing the door and could see me come in; the widower however could not. As I approached, he began to tell the group why he wasn’t happy with the service and the things I had and hadn’t said. The guests were clearly mortified and I, not knowing what to do, simply stood like a statue right behind him. Eventually he finished speaking and I made a big thing of heading to the bar. Mary, was there a way I could have interrupted him mid-flow to indicate that I was there and allow him to save his post-mortem until after I had left?
— Revd H.,