He was fuckin' around with a (probably) crazy-ass bitch, while he's still married.
He (probably) told her it was over, he wasn't leaving the wife & 4 kids for her crazy ass.
She (more than likely) shot him 4 times, then herself, since the early reports are that she only had a single gunshot wound to the head.
Everybody makes dead celebs & sports people out to be pillars of the community, and maybe McNair did do more than most to help kids & blah blah blah. But that doesn't change the fact that he obviously made some shitty decisions, with regard to where his pecker was involved, and it more than likely got him killed.