This is textbook advice from a therapist, and I think for good reason. There is no repair for a relationship while the emotional waters are so muddied. A more insightful therapist might give the advice with the proviso that this is “the textbook advice”, which does something interesting: it allows for the opportunity to allow for flexibility— there may be circumstances in which it is more harmful than helpful to a patient’s well-being to end the affair. And I think in your case perhaps, it offered something else. You were given a test, a choice to make: try to heal the marriage or end it. I think you would say now that you chose the correct path for yourself, the path of new growth, new aliveness, new friendships and lovers. The willingness to challenge the common wisdom and take that first step had to be so hard, and I think I can understand the courage that must’ve taken. This was vulnerable, touching, and insightful and I am happy you shared it.