Getting married in two days she cheated what to do?

I am writing this mostly because I need to get it out of my head and telling the story someone I don’t know will help. I have been engaged before and cheated on before. With that said I have always held a strong in saying there is no coming back from this.
Currently I am engaged to be married and in a couple of days I may be going through with it. My head and heart is heavy with all of this. My current Fiancé cheated on me with her ex boyfriend. And I am up against a wall of torn feelings it seems no one can help. I love her dearly enough to try and move past this. Still it is harder than I ever could imagine.
I should come to find out that the whole thing began shortly after my Birthday with a simple text message asking if I was around because he wanted to tell her something. She assured him that I would not see it. He told her he missed her and wanted her. Although she shrugged it off jokingly she still flirted with him regarding. Plus I was never told.
In December we planned on going to Colorado to visit her maid of honor and enjoy a much needed vacation. She had expressed an interest in seeing her ex but the idea was always short hand like as if we could fit it in. Maybe together. I did not like the idea but I am not the kind of person that’s going to make anyone feel trapped. That’s not how a relationship should be in my eyes.
As things got closer to the trip she stressed more on the idea of wanting to see him. I told her I was not comfortable with it but I am willing to work with her. She knows my past and how much that destroyed me the last time. How it ended that relationship. She assured me several many times that there was nothing to worry about that she would do nothing to ever hurt me and would do nothing to **** up our current relationship.
About 3 days before the trip I come to find out that there has been a mix up with the tickets and that we would not be on the same flight. In fact I would be leaving 3 hours later and be connecting in Cleveland with a 3 hour layover. All and all she would be in Denver by herself for almost 6 hours by the time her plane landed and I got there. She expressed her disappointment but then turned and said to me with some excitement “Well look at the bright side! I can see my ex and we can hang out and get that part over with. You don’t want to see him anyways. And then we could enjoy the rest of our trip.” I expressed that I really did not like the idea. I freaked out at the concept. And further she assured me that nothing could or would ever happen. I asked what if you got high because that had come up before. She gets turned on when she’s high. She expressed that she has complete control and that still nothing could or would ever happen. I would later come to find out that while she is telling me this she is flirting with him. Telling him how she’s freaking out because she doesn’t know if she can control herself around him. They never came out and said via txt that sex was the plan but flirted with the idea often and joked about it. Apparently they had been flirting via txt ever since my birthday in October.
Things got worse as I got delayed in Cleveland. I was stuck there for almost 7 hours and did not get into Denver till mid night. I freaked out of course and 3 times she assured me all will be ok. It was not Ok. Turns out the moment she found out there was a delay she continued to flirt about taking off her pants as soon as she got in the car. And her only excuse for not is that it’s too cold but then again I guess it’s not too cold she said. She told him he wanted him and to hurry. My flight is delayed and she wanted to spend as much time with him as possible.
After I got there she told me nothing happened and I had nothing to worry about. They texted often during the trip and we fought a lot about the texting. I told her I could not understand how someone who never texted you before can’t stop long enough for us to enjoy ourselves together. She always got quiet and never gave me a reason. Just would stop talking. Still we made a lot of good happy memories for the rest of the trip. The txt messages were a mix of stuff when I finally got to read them. Talking about the sex they had and if it means anything.
I found out about a month later when I got to carouse not to look at the conversations. I confronted her and it all came out for the most part. I really had to dig. She explained that she was worried too and when she saw him she felt nothing so the fear was gone. They went to the pizza place and all was good. Then he got a txt from his current girlfriend asking for a paper. I think it was a lie but whatever. SO they went to the house and he looked for the paper. I was very upset she did not fight this or simply wait in the car. After the paper was found and emailed. He took her into his room to smoke. She says she exclaimed that I did not want her to do that and that it’s not a good idea. Still she did it. Standing there after smoking and talking he jump forward and kissed her. She says she pushed him off once but he came back at her again but stronger and harder with the kissing. She says the thought went through her head “well this is it I guess I will need to see if there really is something still here” That is no excuse in my book. He sat her down and pulled off only one pant leg he was in such a hurry. Came very quickly she said and it was over. I don’t know if I believe all of it but that’s the story and she’s been very consistent with it.
Since then she has stopped all contact from him and done all she can to make it up to me. Are love feels real and the holidays were solid. Since then has been too. I have hacked all her accounts and I know for sure that she has not talked to him and that’s a little over the top but she did break the trust first. Now in two days we are due to marry as planned and I am so cross. I love her more than anyone. I have never before been willing to try and work it out. But it has helped to write this all out as I have seen it. Feel free to comment. I would love to talk with someone because I haven’t had the chance too. I am too embarrassed to tell someone I know.