My fiancée (20/F) and I (21/M) have been in a relationship for around 3 years, and she says she has developed feelings for my best friend a week before our wedding.

I know she didn't do anything wrong, but this the worst possible timing to be dealing with this. She says she still loves me, which is great, but I'm not sure how to tackle this. I don't want to be thinking about this on our honeymoon, I wanted it to be nice and intimate. I noticed she's been talking to him a lot when we have hangouts together. I've been trying to be a better person and I've been trying so hard to work on myself and be a better partner, and this is definitely not helping my self esteem. I feel like I'm going to compare myself to my best friend now and I'm worried.

Any advise?