The only way you can save your marriage is to tell her she can NOT have both of you in her life - that you will understand if she chooses not to let go of him but, if she does, you'll be filing for divorce.
She needs to understand this. No equivocation.
I agree. Supplication does NOT work, as it openly kills attraction. Right now, you need to BUILD ATTRACTION, as that sounds like what has been missing in your marriage, and doing the "whimpy" (your words, not mine) thing doesn't do that.
Your wife will begin to respect you again when you begin to respect yourself . . . no sooner.