Yeah it's very complex I don't think they will ever find out the truth unfortunately.
Surely if he wanted to have his wife killed because he was gay he wouldn't want to be there with her when it happened. I know it doesn't make it any better but he refused to get out of the car didn't he. They seemed happy on the CCTV?,
But also like you said, why would they kill her and not him? What was their reason for killing her at all?
If it was an accident and was supposed to be a robbery why didn't they take her jewellery? She wasn't robbed, raped or anything like that, it's just so bizarre. There must be something more to it.