I'm sad

I don't know why ;(
I am really sad and emotional.
This Thursday it's gonna be a nightmare for me.
I never dare to imagine what will happen to me on Thursday :(
I feel so so so so depressed and trust me,
You'll never understand how I'm feeling now.
Looking at all your friends having fun together.
And you'll be staying at home or in school.
Just sitting on your own bed wondering what are they doing..
How much fun are they having.
And when next day comes,
They'll be talking bout all the funs they had yesterday.
And you'll be there sitting and listening to their fun.
And don't even understand a word that they are saying.
All of the sudden, you'll feel like tearing.
I was feeling this for the whole day.
And im really sad of it.
I felt like I'm not included in that fun conversation.
What else I can do?
I try to be happy, but it just doesn't work at all.
And baby you know how I feel,
I hope you'll understand me.