As far as I know, Hatice Cengiz is not Jamal's wife. She claim that she's his fiancee and there are no official documents proving that. Either way, fact is, she's a Turkish supporter/lobbyist for Erdogan and the justice and development party. Erdogan has clearly capitalized on her friendship with Jamal after his death to target MBS.
What was/is still reported in the media is one side of the story published by Qatar's Al Jazeera network and its many subsidiaries in Europe and the US (including Middle East Eye based in London). Reading these stories, you have to factor the enmity between Qatar and Saudi, Erdogan and MBS.
I'm not condoning what happened to Jamal, but Hatice Cengiz should not be involved way more than his actual family.