My sister and father went for a year without speaking because of something my father did to my mother. My parents patched up their disagreement, but the rift with my sister remained. Finally, one day, my sister decided to apologize, even though they were both wrong. Because she took that magnanimous step, our family is together again. Her son is equally at fault, but if he isn't willing to apologize, she should do it.
Life is too short to hold grudges.
The last sentence in your letter is one that should be cross-stitched on sofa pillows and given to each member of that family. In fact, it would make a nifty commercial item, because so many families need to be reminded of this fact of life. Thank you for what could result in a universal olive branch. You have printed a few stories about how well dogs and cats get along. When I had Rupert neutered, he didn't come out of the anesthesia very readily.