Sunshine, yes my x returned a few times at first, just for lunch and sort out the house details he wanted it sold,he took me to view a few houses, but we were never intimate.
He said he always wanted contact, but like you I hounded him until he said no contact was better for me.
He said he had a new life and he hoped the children and I would have new lives too.
It nearly destroyed me and very nearly cost me my life,so I truly know your pain. This man was in my world was my world from being 5 years of age.
No contact was the only way I could even begin to heal. He was right.
When my d nearly died in childbirth I contacted him-against her wishes I have to say and he was a stranger to me. Now I have forgiven him,I doubt my children ever will,but he was a good man and I had the best years of my life with him.
I don't know how or what happened.I never will,but I no longer look for answers.
I could not have been intimate when I knew he had OW.
I will always love him and I would never see him destitute.
I have made a life and I have fantastic kids and now a beautiful g/c.
My life has many blessings and yours will too if you just stop looking for reasons and answers and live for you and your son.
IMO men who leave long term "happy" marriages rarely return.
Sorry thats all I can say.