How does a non-citizen get a divorce?

Question Details:

I am an Brazilian citizen and married to an American citizen. Last year while visiting my BF, he proposed and we spontaneously got married. Not long after, we realized we had rushed into things and decided to get divorced. I live in Brazil and he is a NY resident. I would like to know which ground would be more appropriate for us file the divorce and do we need a legal document to state that we've been separated or just the proof that we're in different countries enough? Important Notice