Emotional affair

My husband and I have been together for 9 years and married for 4. We had our son 2 years ago and i found out a few months ago from the woman he had an emotional affair with that the affair started when i was 2 months postpartum. It lasted until our son was around a year and a half. She only told me because he cut things off when I had breakdown about us feeling like roommates instead of being married. He told her some things about me that now he claims weren'ttrue and he doesn'tknow why he said them, i cant erase them from my mind and it's killing me. I honestly feel emotionally detached from him. He's trying to make things right but he wasnt there for me when i was deep into PPD and was talking to her instead while i was alone. Now I feel like because we have a son i have to try and make things work. I had a broen family growing up and I don't want that for our son. Both parties say intimate photos werent sent and it was all talk. They had been friends since before we started dating. I just need some insight and advice. I dont want to throw away my marriage but at the same time i.dont want to be questioning everything. It's exhausting.