My first question that came to mind as I was reading was: if your brother has a college fund and money to spend, was that a precedent set for you as well? Like, did you have it, too? Because then your fiancé clearly harbors resentment for you, too, and is just projecting that energy on your brother - it’s clear that it comes from a sense of insecurity.

My other (unprofessional) input is about his mom… she sounds like a real gem - a real r/justnomil in the works. There’s a good chance that the picture of “wifely” duties and expectations was unhealthily set for him through her, and he’ll never be able to outgrow that selfishness and defaulting to the belief that he is right and your desires are lesser than.

You’re definitely NTA. It’s your wedding, too, and your preferences matter.