He doesn't believe it was his ex
In his comments he replied in such a way that it's clear he knew it was his ex. You know this OP. Please ignore his attempts to gaslight you.
He has told me he will download it but hasn't yet
Even if/when it doesn't bring up anything, I'd say that's due to some stuff maybe being perma-deleted, also what you have is enough to see he was willing to cheat.
I recently sent a letter to the wife of a married man who has taken advantage of/lied to etc not just me but numerous other women. He's also got off with hundreds of men. I was sincere, I think she should know. I wouldn'tve included stuff that wasn't relevant because it isn't relevant. The point wasn't to say 'these are the things he's done which aren't ok, cheating hundreds of times behind your back, and on the other hand these are the things he said that were relatively ok.' The point was to let her know about all the cheating etc he's doing.
I think what your husband said reflects badly on him regardless of what was said before and after.
It'd be like when my ex said to me that he was happily married, then an hour later asked me to give him head, plus was flirting with or shagging numerous people of both sexes at all times. That he'd said he was happily married I wouldn'tve thought of including (plus he said at other times that he was just with her for the mortgage, her money etc) as I just wanted her to know the dodgy stuff he was upto as I thought she should so she could make informed decisions about her own life.