He’s mad because I pinched him

My husband doesn’t understand his own strength sometimes. He’ll randomly bite me with like the edge/tip of his teeth and that shit HURTS. Or he’ll dig his hand into my collarbone or his finger into my rib cage. So we have our 4yo nephew over and they were play fighting. Our nephew is extremely skinny, he just doesn’t gain weight. So that, combined with my husband not knowing how to play well sometimes, worried me. My husband had our nephew (who’s biologically related to him, not me, but I’ve been around since he was born) In some kind of body lock. Like a head lock, but his whole body instead, like his midsection. Our nephew then starts coughing and I get worried and I pinch my husbands arm to make him let go and he gets angry with me. Saying that I pinched him for no reason. But when he bites me for no reason at all, or does any of what I mentioned above, that’s not a problem? When I was just trying to help my nephew? And several times during their play fight, my nephew said “oow” and asked me for help because my husband is too hard on him sometimes. But I’m wrong? If I’m wrong, I’ll admit it, but I’m tired of him hurting me like it’s nothing and now being upset with it’s done to him.

Me asking if I’m wrong is a rhetorical question. This post is about him getting mad at me for doing something to him that he does to me every day. The difference is I thought I was helping and he hurts me just because.