Confused

So its been done. My husband left yesterday, while I was at work and all i got was an "I'm sorry, but this is the only way it had to be done". And by that he believed it was the only way because i cried every time he said it. Then I came home, Found a letter...not once did it say thank you for the last 6 years...but again it said it had to be done. Also it said...please dont contact me for a while. 
I cannot understand how a human being can be so cruel. I am crazy and stubborn but as mad as I am...I will never leave anyone like this. He left me as if i never meant anything to him. I cried by brains out yesterday...but today..idk its just a miz of emotions...im sad, angry, hopeful for a better future. 
All i know is that he is a coward...and i am so thankful that I have nothing tying me down other than a piece of paper.
I never wanted to fail at my marriage..but as my father said, you cannot blame yourself for failure when the goal involves two people. He failed me, he didnt keep his word, his commitment. 
I am honestly just venting now. Its late and hopefully soon I will be able to sshare my whole story.