dudes, its not wife of bhimsen thapa, its wife of Bhim Malla, a Nepalese deligate for Tibet in Malla Era.
Its said that while he was in Tibet, he did many good things in Nepal's favour. But his enimies spoken against him to the Malla king (forgot the name). When he returned back to Nepal, he was arrested and killed. As the tradition, his wife went Sati with his dead body and before he and his alive wife was burnt, she cursed - "From now and on, in Nepal, those who does good dids may never have happy ending."
That's the reason why Nepal is called Satile Sarapeko Desh.