My fiancée's best friend tried to pay me to break up with her

My fiancée and I have been together for a while now, engaged and planning the wedding. Her best friend from way back has always been kinda weird around me but I figured she was just protective or whatever.

The other day her friend asked to meet me for coffee saying she wanted to talk about surprise bachelorette party ideas. I thought it was cool so I went. She starts off normal then gets all serious and basically tells me that I'm "not right" for my fiancée and that our "lifestyles don't match." I'm sitting there confused as hell because we're literally planning a wedding. Then this woman slides an envelope across the table. I open it and there's a check for $15,000.

She deadass offered me fifteen grand to break up with my fiancée before the wedding. Said it would "save everyone the trouble of a divorce later" and that I should take it as a "head start on my next chapter." I was so shocked I literally just stared at her for like a full minute. She said I could even keep the ring and use the money however I want, and that my fiancée would get over it eventually.

I told her to go fuck herself, took a picture of the check, and left. When I told my fiancée she confronted her friend and apparently the friend spun some story about how I "misunderstood" and she was just trying to help me because she heard I was stressed about wedding costs. Now half their friend group thinks I'm making drama out of nothing or that I was trying to actually take the money. My fiancée believes me but she's torn because this has been her best friend forever. The whole thing is insulting because I already have money set aside for our future, it's not like I need some random payout to be okay. Like what kind of person does she think I am?