Am I overreacting?

My unborn baby’s father and I got into an argument about him hiding things from me (smoking cigarettes behind my back after he told me he quit months ago, inviting people over to our house without me knowing, etc). I hate when he lies to me or keeps things from me when there is no reason for him to do so and he ended up not understanding me at all and calling me names so I just wanted to go to bed and stop talking about it. Well he didn’t want me to leave the room so he got up and started yelling “no youre not leaving me in here alone” and he yanked me backwards by my hair. I ended up slapping him and he yanked my hair again and I ended up leaving, but not before he pulled my license plate off of my car. I wasnt able to stay with my mom like I planned so I came back home about an hour later. He is now saying he doesn’t know why I overreacted and that he did not hurt me, even tried saying that I slapped him before he pulled my hair. Also, I’m 21 weeks pregnant. Am I really overreacting or was this not okay?