Thank you all for taking the time to reply about this. I can understand there are different points of view and it's really helpful to have it all laid out for me to look at. The problem is when something happens like this in a relationship, you can't go and talk to your usual family/friends so it's very lonely and things end up getting wound round and round in my head without being able to talk it through.
DH and I had about an hour's talk just now.
He showed me all the bank statements including other accounts we have, and the only transactions were the 2 £25ish ones he showed me before. No cash withdrawals. He is adamantly sticking to the story that they went for 3 drinks, no dances, and it was a drunken decision that he didn't think about - hence him telling me the next morning.
We talked about how it's been intensified in my head due to my insecurities and he's tried to reassure me that he didn't go there with the intention of cheating or trying to get close to someone else. He pointed out (rightly I suppose?) that if he'd wanted a lap dance or similar, it would have been a planned thing, I'd have never found out.
I think he's surprised by how upset I am and he does seem genuinely sorry that he's made me feel this way. None of this of course takes into account the objectification issue which he admits he didn't think about at the time. Which is pretty shit but at least he admits it didn't cross his mind.
I know it's easy to say LTB. But the thought of ending our entire 20+ year marriage and uprooting our kids. They'd just be devastated. I thought our marriage was pretty good really before this.
How do you get past it? I know it's not an affair and I'm not trying to be dramatic but my stomach is just in knots ever since it happened.