I just read ended someone and I'm absolutely terrified

I was driving maybe 40 km/hr and I looked down at the change in my cupholder because I wanted to see if I had enough for a coffee, then all of a sudden I look up and theres traffic stopped. I slam on my brakes and hit the guy in front of me. Maybe at 20 km/hr.

We didn't see any visible damage to his truck, however my car got a little fucked.

I'm not concerned about that though. I'm mostly worried about him suing. He said he was alright but he doesn't have the best back.

What am I supposed to do now??? Do I contact my insurance company??? Been driving for 5 years and never had a ticket or a collision so I'm kinda freaking out.

I'm in Canada, british Columbia