So my fiance is one of the most submissive girls I've been with, which is why I felt OK proposing to her. She has all green flags (Low n-count, good family, religious, cooks for me, never withholds sex, etc), or did until this past weekend.

After she got home last night, we were in bed together when she got a text from a random number. She had previously mentioned that there was a group of Australians on a bachelor party that the group had seen. When I saw the text, I quickly saw it said "mate."

I asked her point blank if she gave out her number to any guys. She said yes and then I took the phone and read the texts. She said she gave out her number to this guy who sat down with all of them at dinner so they could get them into a club or pay for their drinks. The thread started at 2 AM with him saying that the club he was at was better, meaning she had deleted an earlier message with her telling him where she was. She then said she was back at her hotel, and then sent a wince face selfie. She didn't respond to any more of his messages, until the morning, when she said she hoped he had a good night. He then said to hit him up if she's ever in New York, which is the text I saw. I checked her phone log for calls and didn't see any. She said the guy was short and she felt sorry for him.

She also gave her number out to two other promoters, which she only responded to about getting her group into clubs.

I know everyone will probably say I should next her, but she is begging me not to, asking for forgiveness, admitting she was wrong, promising to never do it again, etc. She said her intentions were only to get her and her friends free drinks or club access, and that she was never alone or isolated with any guy. She offered to let me call her friends and verify she was never alone. Perhaps she really was just using this guy for free booze.

Or am I delusional? Is there any other answer besides calling off this engagement?

EDIT: She said she deleted the text when she got into the club and realized she didn't need this guy. She has offered to download an app that can recover deleted messages so I could see.