My advice (and I need to listen to myself sometimes too): Do not talk about the other person!!! If she is still involved with him she will become defensive and lie. She is infatuated with him, and may feel angry and cold towards you. Or she may tell you that it is over because that is what you want to hear. Just don't go there.
You can tell her how you feel but also take responsibility for your part in the breakdown and apologize for it. Express your unconditional love for her and tell her that if and when she is ready you would like her to honestly discuss your relationship with you and come up with baby steps to improve it.
Again, work on patience. I know, easier said than done - you are a Mr. Fix-it. You can't fix her but you can fix yourself. If you asked your self to write down a list of your faults you probably couldn't come up with too many, right? But what if your wife were to write up a list of your faults, would she run out of paper? We tend to see ourselves through rose colored glasses. Therefore the place to begin improving your relationship is with yourself. You can choose to continue to love your wife in spite of what she has done and in spite of your feelings. Do not let your negative feelings dominate your thoughts and behavior - again you are only hurting yourself. So, go out and have a good day!! Make new friends! Do something 180 - like the running, that is great and will make you feel great too! Hope to hear back, Sheila