Yes - the reality is that she has already 'left' in many ways. She is cake-eating now, having her lover on the side without disrupting the marriage, etc.
Something needs to shake the reality. DB techniques are for YOU. It makes yourself better able to move on if needed, and may also help the WAW to wake up.
However, while she has ANY contact with the OM there is no hope of fixing the M. It is just more cake-eating going on and they will do this indefinitely if nobody changes the course.
So, use the truth that you have in your hand to get the A front and center and on the table. It can't be dealt with if she keeps denying/lying. It sounds like she will do this indefinitely unless, again reality is changed. That is why I taped my WAW - to cut through the denials/lies - I got very tired of trying to get her to acknowledge what she was doing in order for us to be able to work on it.
You can choose to admit to taping, or try to just say you have proof and see if she capitulates.
Either way, you will get nowhere if the truth cannot be discussed and she quits contact with the OM.
ME/XW:47 S21, D19, S15, S14 M:21 T:26 W moved 6/10 I filed 7/10 D final 4/12 remarried 8/12 W wants to R 12/10 and 4/11 but I decline