Hi, hopeful. So sorry you're here, but here you're among friends.
I, too, am a BS (Betrayed Spouse) to a repeat cheater. I found out the first time and accepted her "I'm so sorry", "That was stupid of me," and "I'll never do it again." However, a year and a half later she was at it again and I found out. This time it was counseling, confession, answering questions, etc. I thought we had tackled that issue and moved on, but I found out many years later that I was the only one who moved on. She kept on cheating, and kept adding men to her list.
Why am I telling you this? Cheating can become an addiction just like drugs, cigarettes, alcohol, computer games, anything. She receives a chemical high each time. This is not only from an orgasm, but the secrecy, the danger, and knowing what she's doing is naughty. Like an alcoholic, she may resort to adultery when triggered by something. It may be something from her past, a lacking (perceived or real) in your relationship, something not up to standard within herself, ...who knows? The key is for her and her counselor to uproot this in her life, have her face it, and find a better way to deal with it instead of cheating. If she doesn't, you'll probably be back on here in a year or so facing the same issue all over again because she simply found a new partner.
Don't be that guy! Since this is the second time you found out (and there may be more), you know this is a problem. If she doesn't get the help she needs, she will never be trustworthy. No trust = no marriage. You can help her find a counselor, or whatever else she is looking for, but >> DON'T DO IT FOR HER! << If she's not willing to put in the effort herself to get to the bottom of this issue, work through the digging and asking "why", any change you see will not be from within. Any and all changes in her to make herself a safe partner must come from her, from within her. Otherwise, she'll just be checking off boxes, and when she gets to the bottom of the list, she'll say that she's done all you have asked of her, but there will be no significant change.
I know this because I did just what I'm suggesting you NOT do. I found the counselors. I arranged the talk times. I came up with, well, everything. All my WW did was what I asked of her. Did she change? Nope. Only when I had put into motion our dissolution did I see her start to see a counselor she herself picked out. By that time, though, it was too late. There was no more trust or interest in her from me. Your WW has to figure out - with the help of a professional - the root cause, what to address and change, and how to get it done.
I hope this helps in some way. I felt you should hear that little speech because I get the opinion your WW is interested in stopping that behavior. This is a good sign, and if it's accurate, she is a good woman. It seems she's already making the necessary outward changes (new job, new neighborhood, etc.), AND she makes the necessary inward changes, you can have a great marriage on the other side. It takes work, and sometimes that includes you. Be prepared for some changes on your part. Does this mean you contributed to her choices? NO! But, it does mean you realize you are not perfect, either, and if you both work together on this problem (which is what married couples are supposed to do), you can be happy together for a very long time!
I hope the best for you. Post often and keep us up to date on what's happening. The more information you provide, the more help we can be.