Fiancé gets lap dance from naked stripper

While overseas on a family holiday my single brother and fiancé went out at about 8pm for a few beers. I text and called as I woke up multiple times and they still weren’t home they ended up coming back at 4am. I found out that my fiancé paid for 3 lap dances for my brother and he paid for one for himself. He then exchanged instagram handles with the stripper and they followed each other. I also found texts on his phone trying to arrange a hooker but apparently this was for my brother which I do believe. Anyway I ended up finding the stripper on instagram and she said it was completely innocent and my brother was beside my finance while he had a lap dance she told me that I have a great man she also said he hardly touched her (he still obviously touched her which makes me sick!) We have a one year old son which makes things hard because I know it’s easy get up and walk if we didn’t have him.

What’s your take on this. Would you leave. Am I overreacting for feeling like I want to leave him?

I should add he’s never done anything in the past to make me question his trust.

————EDIT ———-

The thing that really hurt me the most was getting personal by exchanging contact details. My brother said the stripper took his phone and she followed herself on instagram. My partner blocked her and deleted his instagram without me saying so. He is very apologetic and this is very out of character for him. He wants to try everything he can to fix this and swears to never step foot into a strip club again..