How do you move forward from a relationship that had hurt and mistrust when years have gone by.
This question can only be answered with due consideration of your religious and spiritual beliefs as well as those of your family. The impact of both the activity and the deceptive behavior throughout the years that it continued is both sinful and yet a ground for divorce in most organized religions. Having an affair is also grounds for a civil divorce.
If you honestly feel you have erred in your ways by what you have done then you will need personal forgiveness to make yourself whole and able to go forward as a happy and satisfied person. There are many books available concerning the issue of forgiveness but the one person I recommend is usually Robin Casarjian. Her work has been around for a long time and there are many current researchers who continue to use her as an Icon in the field. You need to coordinate your work on forgiveness with your clergy or other spiritual leader. I say this as there are many considerations that are at work in the issue of forgiveness. There is forgiveness of self for your own health and wellness that does not concern others and then there is the forgiveness others grant to you by your community in general. Twelve step programs indicate that one engage in an expansive inventory of how one's behaviors have affected others and involves going to the persons harmed and confessing or at least sharing that information "except where to do so would cause irreparable harm". It is this quoted material that is of essence in your situation and those in similar situations. Who determines what irreparable harm is? How does a human have or gain the power to make that decision? What constitutes what it is irreparable?
These are serious questions and the ones which I would believe may be the source of your ethical dilemma. It also may be the basis of any considerations you have regarding the religious and/or spirituality question. There are differences of opinion regarding what is "irreparable harm" even within twelve step programs. Once one adds the various religious and spirituality cohorts it may become even even more difficult to answer your question. Remember, however, that your ultimate decision, depending on your religious and/or spirituality beliefs, rests between you and your deity or God not you and an earthly being.