I agree although I have wondered before if he could have been involved in whatever happened and Billie is trying to cover it. With the fighting he does he could have accidentally did something he shouldn't have and she was fatally injured. But then the problem for me is that its hard to move past the events of Sunday evening.
I've considered Dd's involvement, too. However, I don't believe wimpy boy toy would take the fall for him, especially after the break up. If he helped in the coverup, he could have pled out of that