To whom/who it may concern!

I’m feeling much better today, although I haven’t told my wife!!
I do like a bit of sympathy.
This morning we met up with an old friend from university whom I haven’t seen for about forty years, and his wife whom we had never met.
We had a lovely time and it really was a pleasure to meet them. I hope we meet again before another forty years pass because I suspect I won’t live to be almost 110!
I don’t think I’ve posted a photo of a small tortoiseshell this year. It’s the blue dots on the bottom of their wings that really get me.
It was nice to see him on this lambies lugs as I’ve always called them.
P.S. I hope I’ve got my use of “whom” correct, or should it be “who”