My boyfriend put my younger cousin and I in an unsafe situation and I am not sure how to handle it?

My boyfriend and I went out with my cousin. He was the designated driver and it was raining. He is normally a safe driver and I feel safe with him. But tonight He thought it was a good idea to take his tire traction off on his truck and drift with us in the car when he was turning. We came sorta close to hitting a light post. Though, we weren’t going super fast maybe 25-30 mph, but it was super scary and my cousin was also scared. We both thought we were going to get into an accident. He laughed it off at first when I got mad in the moment. Later he then apologized many times and said he wouldn’t do it again. I was embarrassed that he did that with my younger cousin in the car, shocked, and scared all in one. I also added that we could’ve gotten seriously injured or worse which he called dramatic. He said he would never let anything bad happen to us but I don’t think he fully gets it and it’s unsettling. How am I supposed to deal with this?
My boyfriend put my younger cousin and I in an unsafe situation and I am not sure how to handle it?
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