If there’s been one gift of writing this, it is hearing other people’s story of what they went through, either as the person having the affair or being on the receiving end. I’m so glad for you that you came through this now in a happy marriage with a combined family of six (!!! :) ) kids. I got the chills reading how your therapist warned that things can get dark, and you saying, “Nah, it'll work out.” (And what your friend said to you! And what your ex said right after euthanizing your cat.) As for your advice, 100%. Leave before the affair. I would add since I wish I’d done this: find a way, any way, to work out your issues with your spouse/partner instead of escaping into an affair. But don’t have one.