Just needing to vent and have some feedback from some 3rd party people

So, I have this friends and let's call him K. So K and I have been friends for a very long time (upwards of 6 years) and are currently best friends. It is important to note that I am female and K is male.

So K currently likes this girl named T. Has liked her for a very long time and selfishness aside, I am happy that they are recently getting along and hanging out with each other.

So, Peter Russell (comedian) recently came to a city fairly far than us. I really wanted to go with K and T. However, K said no, I don't want you to come and cited that because I already saw Russell Peter once it would ruin his experience of the show. I can't help to be hurt by this because I feel very excluded and almost "not wanted" by the person I call my best friend. And I've been upset by this for two months and even after the show was done (yesterday), I'm still bummed out that I couldn't share it with them. I don't know why this is such a big deal, but I can't get over it and it's making me very very sad.

It's also making me very irritable at him and I can't help snapping at him for little things. What do you guys think?