I've tried to keep an open mind from the beginning to now. I'm absolutely convinced he killed her and disposed of her or asked someone to help him dispose of her but I'm still undecided whether it was murder or manslaughter. My opinion is changing all the time.
On the one hand, I still doubt he has the guts for murder. I'm having pictures in my mind of them having a fight and him trying to quieten her and accidentally blocking her nose and mouth at the same time, causing her to die.
Then again, I doubt that she'd be the kind of person getting hysterical anywhere close to her children and risking that they'd be affected in any way. This means the wouldn't have been the need to keep her quiet and therefore no accident. Which would lead to the conclusion that is was cold blooded murder.
Either way, he should spend many, many years behind bars.