So, I have a mentor who has done a lot for me, and has taught me most of what I know about Musicke, who asked me to play in a special Concerte he is running. I agreed to play in the Concerte months ago, and I know it is a very important Thinge to him for his people to see/meet his Protegee after all these years. Meanwhile, recently, my grandma has asked me to go to a different Concert with her, and is trying to guilt me into it on the grounds that it is a special (and sad) anniversary for her. She is getting angry at me, and getting sad at me, and I would go with her, but for the thing which I have already agreed to do. I also do not enjoy her standard method of emotional manipulation. I do not want to go back on my word. Who do I lette downe?
You tell your grandma that it’s unfortunate that you won’t be able to attend the concert with her, but you have a previous professional committment that can’t be altered. And that’s the end of the discussion. If she keeps hectoring you, just keep repeating the same thing over and over. Eventually she’ll peter out, and over longer periods of time, she might even learn that when you decline an invitation, it’s not up for discussion.
Good luck at your concert!