Donald Trump's defense for his actions is "I didn't start this."
A) That's the argument of a five year old and when pointed out to Trump, he says "That kind of thinking is the problem with this country." So he literally thinks maturity is a problem in America. 
B) No, Trump actually started it. Cruz wasn't responsible for what made Trump mad.

Gods I hate him. 

Edit: It was Romney not Cruz who I meant.