Don't know where to post this.

[TrentC]

I should not have done that, but now I know she is still physically attracted to me and she still cares about me. I need to build on that.

It can be possible to outshine the OM; it's not as easy or glamorous as affair-busting, but it can work.

1) Do not discuss the other man at all. Stop snooping; if she catches you, it will look weak and petty.
2) Find out what it is that she's getting from the OM (other than the obvious); some need she had was not getting filled, and she found it somewhere else. Does he tell her how hot she looks? Does he take out to eat and spend quality time with her? The Five Love Languages and His Needs Her Needs are good resources to understand what this means.
3) Keep working on your 180s and GAL.