He said in OP that he hates her. It can't get much worse than that.
He obviously doesn't
hate her, he's just bothered by her behavior. Hate is a very strong word and very few times when it's said is it actually meant. But at the point things are now, you'd be surprised how much this matter small matter could destroy. But likewise, you'd be surprised how very much it could build. One must choose which path to take and then act upon it.