I've never known Frank to hold back so I think all he is saying is LLRT - tell her the affair is to end or split.
It would seem that you are there already and as much as I would stand behind you and fight - you just don't have a worthy adversary. Until she figures out what she wants to do (with her life, OW, etc.), you'll be a world of limbo - going out of your mind. Time to save your sanity. A lot easier to type from my point of view, but she is a disaster waiting to happen (well, is actually happening). Time to focus SOLELY on tyler and his children. Let the drama go.
My .02 - you have fought valiantly, time to save yourself...
Sven
Never sacrifice the great for the good. Sometimes the beauty of grace is that it makes life not fair.