Khashoggi, a prominent critic of the Saudi government in Riyadh, was murdered at the Saudi consulate in Istanbul, Turkey, in October 2018.
Hatice Cengiz said the £300 million ($408 million) takeover deal was "heartbreaking" for her and she was "very disappointed".
Aljabri now claims that the Saudis and MBS had sent an assassination squad to Canada to try to kill him, and that members of the squad were part of the team that murdered Khashoggi.
Khashoggi, a Saudi-born US resident who wrote for the Washington Post, was an outspoken critic of the Saudi leadership, with which he had once been close. He was murdered on October 2, 2018.
The news came hours after police confirmed that around 15 Saudis, including officials, arrived in Istanbul on two flights on Tuesday and were at the consulate at the same time as the journalist.