I am totally confused. Some experts say confront others back-off. I am not doing this due to passive behaviour. I'm doing it based on what to do when W doesn't admit the affair when confronted. I already have confronted her. I will be assertive and express my feelings. Reading self help confuses me more.
Just confronting her usually doesn't do anything. She will either lie to your face, or tell you she doesn't care. The point is that you have to have more than just confronting her. Do you understand?
If you are too scared to tell her to stop, or you know you aren't going to back up something you tell her, then what good does it do to confront her?
In your case, you have already confronted her, but that's all. She lied about it. So, now what? You have tried to ignore it for a long time and it has not gone away. I understand depression, but is this the way to deal with your health issues? Do you get suicidal?
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!