Am I wrong to be mad at my boyfriend?

So my boyfriend and I work together at the same shop, but in different departments. We drove separately (we live together) to work because my department was supposed to get out 2 hours before his. I ended up having to stay over so we got out at the same time.

While driving home he was behind my car the whole way home (30min drive). During the drive home I noticed in my rear view mirror that he was occasionally swaying over the white line on the side of the road, and he kept randomly slowing down going like 5-10mph under the speed limit. When he would catch up to me at stop signs/traffic lights, every single time I looked in my rear view mirror (when he was close enough for me to see his face) he was staring at his phone, with his head down. Most of the time I looked back I could see him staring down towards his hand, a few different times he actually had his head up but had his phone in front of his face, very clearly in view.

When we got home I immediately confronted him in the driveway and asked why he was on his phone so much. He said he picked it up once briefly to change the song playing. Other than that he completely denies being on his phone. He also entirely denied swerving or slowing down. As I was getting ready to get in the shower he followed me into the bathroom. He looked straight at me and said “you must be blind because I wasn’t on my phone, I don’t know what you’re talking about”. I told him to get out of the bathroom. Then after getting out of the shower he kept trying to come up to me and joke or kiss me, etc, acting like nothing happened. I ignored him, and once he got in the shower awhile later I left to go grocery shopping.

The shopping needed to be done anyway but I left mainly because I am so irritated by the way he completely denied it then acted like nothing happened. I saw it plain as day and he acted like I was crazy. I’m sitting in the parking lot and haven’t even gone in to the store yet because I just want alone time to cool down. I’ll talk to him later but I don’t want to right now when I’m so irritated. Am I overreacting?

Also I should mention, early on in our relationship (we’ve been together 3 years) I frequently would have to tell him to get off his phone while he was driving with me in the car. He would always be texting or trying to read a whole damn article. A few times I even had to stop him from watching YouTube!! While he was driving me! And I promise you, he was not driving well while doing all that.