Mr Singh had quit the BJP and joined the Congress in 2018.
Former MP Manvendra Singh Jasol's wife has died in a road accident in Rajasthan's Alwar on Tuesday. Mr Singh and his son were also in the vehicle involved in the crash and have been injured, police officials said.
Mr Singh, son of late BJP stalwart Jaswant Singh, was the MP from Barmer between 2004 and 2009. He had quit the BJP and joined the Congress in 2018.
Police officials said the former MP's wife, Chitra Singh, was killed in the accident, which occurred on the Delhi-Mumbai Expressway, near Khushpuri village. Mr Singh, his son Solanki Singh, and the car's driver were injured and are being treated at a hospital in Alwar.
A police officer said, "The car was headed from Delhi to Jaipur. Doctors have said the injured are out of danger."
Doctor GS Solanki from the Solanki Hospital in Alwar said Mr Singh has suffered chest injuries and rib fractures. "We were informed about the accident around 6 pm and the injured were brought in some time later. Chitra Singh died on the spot and was brought dead. Manvendra Singh has suffered chest injuries and rib fractures, and pneumothorax (accumulation of air around the lungs) has also been noticed."
"Mr Singh is being given blood. He is conscious and has suffered no head injuries. As of now, he is out of danger, but he will be kept under observation. His son has suffered minor injuries," the doctor added.
Extending her condolences, senior BJP leader and former Rajasthan chief minister Vasundhara Raje said, "I am saddened to hear the news of the demise of Mrs Chitra Singh, wife of former MP and MLA Manvendra Singh Jasol, in a road accident."
"I pray to God to give peace to the departed soul. I express my deepest condolences to the bereaved family members and the residents of Jasol. Shri Manvendra Singh and his son are also injured, I pray for their speedy recovery," she added.