When is playfighting too far?

Yesterday me and my boyfriend were joking around, I thought, and playfighting. But then he said he was actually annoyed at me and proceeded to hit me on my body, not my face. He did it a couple of times. It felt like he was proving a point. Is this too far? He’s never actually hit me out of anger or annoyance before so I’m a bit shook he took the physical route.
When is playfighting too far?
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