I'm sensitive

So today I decided to go through someone's facebook account who I should be really close to.
I have known this person since birth, I see them regularly.
BUT!
And this is really bugging me.
When I was going through this account, I noticed something. I started to feel a strand of jealousy and anger burn up inside me.
This feeling was caused by something so little.
And so stupid.
This feeling was caused by a single photo.
A photo of this person at their year 10 formal.
It made me a little bit sad that I wasn't a part of it.
THAT AT SOME POINT
In this person's life, I wasn't there.
AT SOME POINT
This person missed out on a part of my life.

It's funny because, I used to be really close to this person.
And now, I see them building a close relationship with Tegan.
I'm not quite sure how I feel about it all to be honest...