There's a piece missing Saca...
If HK$ gets rid of Anna - what value does KE provide?
If KE has done some of the dirty work for him - he owes her.
Unless he plans to turn her in to the authorities as the quack killer...in which case he will have covered his own tracks perfectly.
The most difficult crime to prove is killing a druggie with drugs.
She provided the drugs. He provided the access AND permission.
He's copped out of the "we were married" thing with the "we were REALLY going to be married" thing, because a husband has duties and obligations.
I'm sure KE has a bank account bigger than you or I ever dreamed of.