The former Girls Next Door star slammed Harris - who eventually tied the knot with the Playboy mogul on New Year's Eve - for her previous actions.
She told Montana's Big J Radio Show: "I got pissed off when she hurt him and he can't go around thinking that people will automatically love her, especially after that. That pissed everybody off, that she would just leave him and dump him, use him and abuse him.
"Of course, someone like me, I wanted to kill her. So now he's trying to get people to love her again."
The 27-year-old - who next appears in the ABC diving competition Splash - spoke with Hefner at the Playboy Mansion recently, and the 86-year-old assured her that he has no regrets about tying the knot for the third time.
She said: "It was just me and him and I looked him in his eyes and said, 'Hef, are you happy?' And he's like, 'Oh, am I Kendra! I've never been this happy, and I want you to tell everybody that'."
A source has revealed that Hefner and Harris, 26, signed a prenuptial agreement before getting hitched on December 31.
His estimated $43 million fortune is promised to "his children, the University of Southern California film school and a variety of charities".
Wilkinson said about the deal: "Of course there's a lot of gossip about that stuff. Nobody really officially knows. Not one soul knows about that except for them."