Can we not pretend OP acted thoughtfully, cleverly and with honour. She got pissed, upset and messaged the wife
I think it’s subjective on whether you think the wife should know or not. You don’t know what’s going on with her, her physical or mental health or the state of the marriage. It’s an area where you should never rush in.
The woman could be ill, suicidal, in an abusive marriage, and clearly it’s not quite as simple as “she’s now got the ammunition” . No one needs ammunition to leave a relationship. And someone in an abusive relationship often doesn’t leave easily. So this may have piled more pain on her. It may also be a surprise and she thinks fuck you and goes, but thats unlikely due to the level of scum he is. We also don’t know if there are kids involved.
Anyone saying the op is wrong , is not doing so because they feel the wife shouldn’t have been told, but because the op got drunk ans spiteful so decided to try to hurt the wife as well. And she went to town, she didn’t just give evidence, she sent the messages, sex pics (notice plurals) the lot. Likely because she was drunk, spiteful and trying to cause pain.
Ultimately there are ways to do this, to tell someone, to ensure they know without doubt, but to also minimise the pain you cause, to understand if they want to know, and how much they want to know, and the op didn’t do that.