Superhurt - I'm very sorry this has happened to you. It's devastating, I know. You'll get a lot of good advice and support here. We'll say different things, different POVs, but I think most of it will be useful in some way.
There's a lot of people on here who are finding out about affairs many years afterwards. It's not uncommon. I think there's a whole section devoted to this and a lot of threads. Maybe it would help to see how others have handled this. Understand that while a lot of physical time has passed, this just happened to you, because you just found out. It's fresh, and puts your wife and your marriage in a very different light now. I think IC (individual counseling) might help you especially if the marriage has been otherwise good, to integrate this into your feelings about your marriage in a way that gives it an appropriate place in your lives. As you say, you're not the same person yourself you were 14 years ago.
I do agree with others here that you should tell the Church authorities. Perhaps not proclaim it to the parishioners but the authorities should know they have a man like this who may be preying on his flock. This sounds like what happened to your wife. People like this kind of sinister minister (and there are others in other types of power positions) are there to listen to people's problems and help them over the rough patches especially with scriptural guidance. They give a shoulder to cry on. A predator starts with the shoulder to cry on, the kindliness, the warmth they may feel lacking at home, and they know how to manipulate a vulnerable person into feeling things they shouldn't - transferring affection and emotion to them rather than the spouse - and doing things they shouldn't. I would be willing to bet cash money that your wife is not the only woman this guy has done this to. It's a despicable thing to do to a vulnerable person. I would bet there are others and he might have a whole history of this. I understand your concern for his wife, which is admirable, but I think predators have to be stopped and the first part of that is often establishing a pattern of behavior - documenting it with superiors and to enable them to start watching and investigating. I would bet that his wife is hurting anyway as there is probably something deeply wrong in their marriage and sometimes, things just need to come out. We can't protect the guilty because there is a family member who might be hurt. She will need to be consoled by people in an appropriate way after the fact if this comes out. To tell the authorities is what I would advise as well. This is the thing with affairs - everyone involved gets hurt in some way when they come to light, it's unavoidable.
Obviously don't beat him up or engage in violence. I fully understand this desire, it would be my first instinct too, even as a woman, but it would only cause tremendous trouble for you and your wife and family, and make him look like a martyr. Exposing him to his superiors is a better form of revenge - I DO believe in revenge but it has to be practical and legal - and it would probably make you feel better and also expose someone who might be a real predator to his congregation. Of course, if this was a one off for him as it appears to be for your wife, the authorities would undoubtedly consider that as well.
Be prepared for a lot of ups and downs in your feelings, it's a roller coaster ride from Hell, but you sound like a solid and stable person and it does seem like this was a one off for your wife. I wouldn't let this predation by him wreck what might be a solid relationship, especially now, for you two, especially if your wife is showing the proper regret, remorse, and willingness to do whatever it takes to help you handle this. Good luck to you both!