I and my wife have been separated for 6 plus years. I am in the USA and she is in Nepal. I can not go back to Nepal because of my immigration issues. As we all know, for a man to file a divorce in Nepal is very difficult and long process. She is demanding huge unrealistic amount as a negotiation for divorce which I can not fulfill.

I have read some post that some Indians have filed a divorce in the USA even though their wife is in India. Anybody knows similar cases for Nepal?

If you know any attorney who has handled such cases, please recommend.

It is very difficult to get a divorce for a male in Nepal. Basically you have to wait for her to file a case. You can have your parents deal with court on your behalf by signing over in front of notary /people from embassy. Then case will be decided on court, where she will get her share from your property. It doesn't matter how much she is asking for it, eventually she will get what she is entitled legally but if you are in hurry then you will have to come in terms with her.
And for attorney, please ask someone backhome, and depending where in Nepal someone will be able to help you.

Nepal ko law (US ko pani same nai chha) heavily favors women.