Personally I think he sounds a bit immature but you sound like you're overreacting.
But around here the thought police are always out in force with extreme reactions.
What (probably) actually happened: he danced with someone, it massaged his ego a bit, he did not in fact do anything even vaguely resembling cheating.
You asked about it in a joking way. He replied similarly, probably partially because he thinks about it in a "laddish" way (this is the immaturity), and spoke to you about it more like a mate than like a woman he was in a relationship with - not to be mean, just being unguarded, and partially because that's how he interpreted the tone you asked him in.
You then took what he said in a way he had totally not intended, and basically accused him of cheating. He (IMO justifiably) defended himself, because thinking about kissing someone or getting their number is not at all the same as doing it.
And then he's angry at being accused of cheating when he didn't, and you're angry because you feel disrespected because it's now more in your face that he could find other people attractive, even though that's normal.
Storm in a teacup misunderstanding to me, on both sides.