SM34: having gone through a similar, albeit thankfully short, affair on my W's part, which I tolerated while it lasted, and via this tolerance got more time in my marriage, I think you pay a long term price - yes, she may come back to you, but you have lost face and respect in her eyes. A transitory short term gain for a long term loss - not worth it, in my book.
M58, xW54 S22, D18 M 1984, D 2016 Living a new life.