In general I have no objection to my dh having friends of either sex but a woman he has previously had an affair with? No way!!! It doesn't matter how long ago the affair was it's a terrible betrayal and the fact he claims he worries about her indicates he still has feelings for her. If he had any regret about the original affair and how it must have affected you at the time he would steer clear. He must know that his continued contact with this woman is bound to make you feel very insecure. The fact he has kept this contact secret indicates that he knows it would upset you. Doesn't matter if there's a lot of water under the bridge and the friendship is entirely innocent, his focus and priority should be on how his continued contact with this woman makes you feel ...not his own wish to stay in touch with a woman he betrayed you with.
I have no clue about whether I could continue with the relationship or not in the same circumstances but I do know that for all the reasons you state I might well come to the same conclusions as you. It is not always best to break up a very long relationship which is still happy in many ways. Good luck op. Hope things work out well for you.
Ethical question - how do you feel about second chance??
Unite the Kingdom and Pro Palestine marches Cup 16th May 2026


