Long term affair that resulted in a child

I was separated for almost a year when I met this man and we became friends. Truly only friends no sexual contact whatsoever. After almost a year, he and I became intimate a few times not knowing he was married. This resulted in a pregnancy. When I told him of the pregnancy he basically told me to have an abortion b/c he was married and was having infertility issues with his wife and did not want to bring this to her. They had been trying to have a child for almost 9 years and could not. I confessed what I done to my husband who chose to stand by me and convinced me not have an abortion (wouldn't anyway) as it was not the childs fault. I have a beautiful little boy that shares my husbands last name. The man and I did not have any contact with each other for several years when he contacted me to tell me how sorry he was for how he treated me and the lies he told and could I please forgive him. We exchanged a few photos when he realized the resemblance in my son to him. So he confronted me and we have lived with this secret for years. When my son was 3 the guy told his sister of the affair and the child he had with me. She has met my son a few times but said she would never say anything. Over the years me and the guy talked on and off until a few weeks ago. He contacts me and says he wants to know his son and feels a lot of guilt and that he is a blessing from GOD but he does not want to destroy his family or mine. This has kept me on an emotional rollercoaster. He has a child with his wife that is 2 1/2 months younger than my son. I have a second child with my husband. Long story short the lies, deceit keep growing. Now his entire family knows and cannot believe what he has done and want to be in my son's life. The man would not tell his wife the truth so I did a few weeks ago. He told her it was a one night stand and that he found out about the child a few weeks ago. He did not know he was his and does not even have his last name. Which is true b/c my husband did right by the child. I do not want this man anywhere near me, my child nor does my husband. I do want the wife to know the truth though that he abandoned his child and now since he has been exposed he wants to play the hero and get a DNA test and do the right thing and be in my son's life which will destroy everyone. He has told the wife I am a stalker and not to contact me and so far she hasn't. I have so many emails, photos, phone conversations etc. proving he is a liar but can't get her to contact me to tell her the truth.

Now my question. Should I care if she knows the truth? Should I let this man be in his life?