(18F) My boyfriend (18M) danced with another girl. Am i stupid for feeling bad about it?

My boyfriend went out to a graduation party for one of his friends. Everyone was drunk including himself, we didn't talk a lot when he was partying- partially because it was so late (11pm-4am)

Anyways i woke up to a message of him saying that he needs to tell me something and not to be upset because "i handed the situation with respect towards you and you in mind"

he ended up sleeping late into the afternoon and told me he randomly got confronted by a girl that he graduated with last year and she took his hands and i guess they danced. I wasn't there obviously becuase i don't live near him to attend everything he goes to.

He said the girl was dancing with alot of other men and that shes the long term (5yr+) girlfriend of one of his friends. He just said the dancing contained spinning but again, only his words. (he's never danced before)

Haven't talked to him alot today after he told me (we usually talk alot) because i have trouble regulating my emotions in moments like these. I wasn't me or anything, just jealous i think...i've had a few h to comprehend it.

i do recognize dancing is harmless fun but i also have the strong fear he's lying and touched her in more intimate ways than just 'spinning'... my previous long term relationship ended with him cheating on me so i still have a deep emotional scar from that.

So, What do you think?

TL;DR- boyfriend went to grad party where everyone was drunk. danced with girl that was taken, paranoid and upset with the fact he danced with another woman.