My H slept with his friends wife. This woman had fallen for my husband I could see this happening and had asked my H not to stay at the friends house while away on business. He told me he would never do something like that to a friend and how dare I even think that. So I told myself nothing would happen. Guess what she got into bed with my H asked him to bring condoms on next visit and the rest is history. Except her H found out they had a big discussion unknown to me at the time and decided they would just be friends.

Fast forward a few months her H got p****d off and phoned me and told me my H had been to bed with his W. SHE actually phoned me and told me it was something that JUST HAPPENED. My response we all have choices and YOU chose to do this it did not just happen. She also told me MY H was very special to her as a friend and she actually really liked me as a person. My response was over my dead body would there be any continuation of any friendship if I CHOSE to stay with my H.
From that day my H never spoke to her again ever drove her crazy as she really believed what they had together was something special.

Do NOT kid yourself that this A is anything other than him having his cake and eating it. Tell him to tell his W about you two and watch him squirm and please spare yourself more hurt than you've already been through.

If you really thought you had something more than an A why would he not end the first R before beginning one with you. THINK you have choices right now you're making a bad one for you his P and the future.