My (21F) boyfriend (21M) threatened me with a knife as a "joke"

I really don't know what to do. This afternoon I went to visit my boyfriend. Everything was normal. I brought him a homemade scone.

We got into a playful tiff when I tried to hand him the scone -- genuinely playful, he wanted me to put it back in the box for a second, I wanted him to put it on the table so it didn't squash my scone. I was holding out the scone saying that I'd put it on the bed if he didn't take it (he is a bit OCD about crumbs on the bed, and he kept saying "put it back in the box, but it back in the box". We were both being silly.

Then out of nowhere he picked up an open Swiss army knife from the bed and pointed it at my face while commanding me to put the scone down. I was sat down on the bed and he was stood up. There was a very surreal moment where I stared at this knife that my boyfriend was pointing literally inches from my face. I felt disembodied. I lowered the scone back in the box while staring at the knife, then he stepped back & threw it back on the bed.

There were these few seconds where he went back to what he was doing and I was frozen there wondering what had just happened. I was like still in shock and deciding whether to say something or pretend everything was ok. I think he must have looked at me and realised I was upset, because he knelt down and put his face next to mine like he usually does when I'm starting to cry.

I did cry a little in shock I think, but also went ballistic. I flung my stuff in my bag while swearing and shouting, shoved him out the way when he tried to stop me from leaving and just ran out of there. I wanted to get away from him. The whole time he was like "oh my God, you're overreacting, it was a joke".

He's texted me since and he's sticking to that. He says that he's sorry for doing it but my reaction was "irrational" and I was "overexxagerating the situation" because it was a joke. I'm so upset that not only did he do this, but he hasn't even had the decency to be like "I'm really sorry, I fucked up so badly and it will never ever happen again. I don't know what I was thinking. I meant it as a joke but I realise now it wasn't funny." I think he's refusing to acknowledge that what I feel is valid, because he feels that would be also acknowledging he behaved like a monster and he doesn't see himself like that. But that's not good enough for me. My immediate gut feeling in the moment was "this is not ok".

He's never done anything remotely like this before, but he is a bit posessive. I'm like a millimetre away from ending our relationship. My friend agrees with me that it was not normal behaviour but he keeps on saying it was a joke & I'm being irrational. I think the only reason I didn't dump him on the spot was because I couldn't manage many words beyond: "what the actual fuck".

So what do I do here? I can't stop picturing that knife in front of my face. I don't want staying together to become a literally fatal mistake. But I also find it hard to believe that my boyfriend is an actual abuser rather than just a fucking idiot. I'm so confused.

TLDR; Boyfriend waved a knife at me during a playful tiff. I was scared and am contemplating dumping him, he claims it was a joke. What do I do?