Trump’s insults about others have been much harsher than “maniac”. He says Hillary has killed hundreds of thousands of people through her incompetence (true). I don’t think he actually dislikes Cruz if “maniac” is the best he can do.
Saw a cute quote in article from Iowa:
“Trump’s pretty blunt,” said one Iowa farmer, “Cruz can tell you off and not hurt your feelings.” _:)
The insult wasn’t “maniac”, it was “a little bit maniac”. There is a difference. They probably planned this out.
You're keying on the wrong part of Trump's criticism.
Trump used the word maniac to describe Cruz's behavior in the senate. That's similar to the way McConnell, McCain, Lindsey Graham, Harry Reid and Big Media has described Cruz's behavior in the Senate.
Trump's attack is from the left.
Trump was very careful to only hit Cruz back with what Cruz said negative about him—they’ve questioned each other’s temperament and judgment.