You must go together to the amphur for an amicable divorce. As far as I'm aware, to force a divorce through just one party you must have separated for 3 years. In case the divorce is disputed, there should be no financial support given during those 3 years or the court could consider the couple 'not separated'. If he is living in his home country he should be able to divorce you from there? And then you can register the divorce papers at your amphur?