I don’t remember the details but Trump said something to her about a year ago that was pretty bad. I don’t think she is GOPe. I think it is personal between them.
I don’t know the details either, but we do know Trump never strikes first. Malkin must have ripped him pretty good, and Trump retaliated. As a Trump supporter I’ve had his Malkin-insult thrown in my face a fair number of times. It’s not a pretty one.