Ouch, I can see why that would hurt. You would think that a friend would ask how you're doing before anything else. Especially if you have gone through any kind of medical surgery or appointment for that matter. That should be the very first thing on any friends mind until they knew things were okay. I'm so sorry to hear that this friend has let you down so hard.

Some people are like that don't like to talk about "difficult" things in their opinion and think that going to a concert will make you happy. They themselves often like to distract their minds and life like that to feel better. Many have good intentions but are inappropriate

Surgery for what?

what was the concert?