Divorce Support Forums: blackmailed by husband

I married my husband in Cambridge MA in 2002. I am a non-US citizen and he is American. In 2005 due to family reason I returned to my home country. Since then we hadnt seen each other for over 2 years and our marriage gradually breaks apart. We talked about divorce since last July. However, although he agreed to file for divorce, he kept delaying the process one month after another meanwhile requesting me to pay for filing fees etc. I sent him the money but still he didnt do anything as promised. And I start to think he will never do it. He is simply using this issue to ask for more money from me.

It seems I cant initiate the divorce since I dont live in MA any more. But is there any way I can do it, such as having a person representing me in this case in MA?

Also, he told me that the only form we need to file is Separation Agreement. Is this correct? What kind of forms I or he should file if we both agree for divorce?

I am desperate to get some advice on this issue. Truly appreciate your help.