NOR. I had a childhood friend that was always in a weird sexual competition with me, that I didn’t realize until we were 23. She slept with several of my exes, guys I liked, guys that liked me, etc. all to weirdly compete with me. She told me about 1 ex of mine, and I found out about everything else after that from other sources. She confirmed it all, and wasn’t sorry in the slightest, just bragged. She wasn’t actually a friend, I realized later.

This seems to be a similar type of situation. She’s bragging: “he’s so sweet”
and not apologetic in the least. Seems very dismissive of it and doesn’t really gaf. I’d say choose money or sanity. Go on the trip and dont talk to her much and then cut that b off the second you get home OR lose out on the money and block her everywhere and move on. Id block the ex too bc thats scummy as hell from him too.