A friend who betrayed me

My dearest and oldest friend,
you have put our friendship to an end.
It is you that I depended on,
what did I do that now you are gone?
In your bad times, I've helped you,
I thought my friendship grew.
I believed you, but you broke my trust.
For you, I'm mixed along with the dust.
When I really needed you to help me,
just to do a favor, you didn't agree.
For that, I've lost something great.
You have closed the friendship's gate.
When we meet each other, we ignore.
For each other, we don't exist anymore.