D@mn B - when you get going, you really get going.
Honestly Pain, I have to agree with a lot of what he has said. When I read your posts on other people's threads most of the time I think here is a man who understands the tools here, who is trying to help others to understand and implement them. But then I read yours, and I realize that whilst you understand it on an intellectual level, like all of us to some degree, you have difficulty putting them into practice. Your actions are reactionary. They are fuelled by emotion and expectation. Think, breath, then decide how you will act. Act with dignity dignity does not mean being the nice guy. Dignity means acting in a way that is true to yourself and allows you to hold your head up high.
I know how hard it is to detach when you have kids. Going dark really isn't an option for us. Think of her as the nanny. Someone who helps you look after your daughter. No more no less. The nanny gets an STD. Would you care, should you care. Would you be offering to give her a lift to the emergency room. No, you would not.
Your W has an STD. The answer for me isn't "It isn't any of my business" it would have been "that must suck" then change the topic "do we have any milk?".
I read on someone else's thread (can't remember which) something and I am paraphrasing ... "[their] problems are not [your] emergency". Leave her to deal with her sh!t.