How do I cope with the pain and anxiety of unrequited love and loneliness?

I was in love with my flatmate and she just left to go back to her country.
We didn't talk for 3 months , not even today.
I feel that I wish I could grab her and not let her leave.
But sadly I can't do that to her.
We had a fight about 3 months ago.
After that I tried to talk but she just ignored me. So I waited.
Maybe it would solve itself. But it didn't.
Now I am feeling all alone and had an anxiety attack.
The love I had for her has been unanswered..
And I didn't get the last conversation.
I wished she loved me.
But you can't force anyone to fall in love. I will move on.
Love hasn't been kind to me. I feel I am a failure.
I like it myself dying inside today.
How do I cope with the pain and anxiety of unrequited love and loneliness?
Post Opinion