I'm not sure if I'm somewhat blessed or if I'm just a bad person, but whenever I have had a falling-out with family members or those outside, they are just gone from my concern.
I don't dwell on it or have any feelings of regret or loss, nor do I have any lingering anger or wont for retaliation. My wife used to tell me that she just could not understand how I was able to randomly mentally and emotionally delete people from my life. I, conversely, could never understand how people can maintain pseudo-cordiality with people they can't stand.
Had I received a letter from my maternal grandmother akin to the letter your partner received from his maternal grandmother, I would have probably used it to ignite the barbecue.