What should I do

Jessica
I need advice. My parents split a year and half ago. My mom met this new guys and we moved in, I like him. But I don't like his dad. We butt heads all the time and last night was the last straw. He called my boyfriend 
A terrible person 
Has no respect for him 
And that he is going to break laws and be in jail.
Yes my SO drove home on HIS ATV and here in Ontario you need to have your g2 (licence class) and he only has his g1. We didn't know till yesterday that's was the law since we go pulled over by a cop. But my boyfriend had no ride home.
SO! Since this guy is rude and very opinionated, he decided to insult my boyfriend who he doesn't even know.
My boyfriend and I have been together for a year, he is joining the military and has the biggest heart. He is helpful around his house, does yard work, etc. And just because he broke a minor law he dislikes him. 
Do I have a right to be upset, and if so how do I tell him. 
Btw my mom isn't helping, I want to move out so I'm gonna try everything before I leave.