AITA (Fanfic writes)

Am I the asshole for entering a poly relationship with my future in-laws?

(Bella Swan Sibling x Carlisle x Esme)

I, 22 female/male/enby, was attending college in California when I received an invitation to my younger sister Bella's, 18 female, wedding.

I wasn't jealous or upset, but in fact overjoyed. I immediately called my sister and asked if she needed help planning the wedding. She accepted my help and I took a three month sabbatical to help my sister's future SIL, Alice, in planning Bella's wedding.

It was there that I met Carlisle (30 male) and Esme (28 female). My sisters future FIL and MIL and I immediately developed crushes on both of them. I'm bi and have an interest in polyamorous relationships.

They seemed to like me as well and even flirted with me. Esme had offered me some cooking lessons and I graciously accepted, Carlisle found out that I was studying to be a doctor and immediately offered to sponsor me. I started spending a lot of time with them because of this and helping plan Bella's wedding.

After being there for two months they asked me out, to which I happily agreed. We went on one date, which was dinner at a nice restaurant and we agreed to attend Bella's wedding together.

The day after our first date Esme and I discussed what we would wear to the wedding and Alice suggested that we wear matching dresses to which Rosalie (my sister's other future SIL) agreed that it would be adorable. My sister walks in with her fiancé, Edward, and asks "What would be adorable?" Alice answered "For Esme and (Y/N) to wear matching dresses!" My sister laughed and asked why we would do that.

I realized that I had forgotten to inform her of my relationship with her future in-laws and explained to her that I had entered a relationship with them.

Bella was livid and started going off on me. She called me a lot of horrible names and called our mom and told her that I was trying to ruin her wedding. My mother, stepdad, and future BIL blew up on me as well and demanded that we end the relationship. My dad doesn't care about my relationship with Carlisle and Esme, but said that it would've probably been better to tell my sister after the honeymoon.

I'm hurt and upset by the entire situation. Carlisle and Esme don't want to end our relationship and neither do I. I've never felt this way about anyone before, and I want to see where this relationship goes, but I don't want to hurt my sister for my own selfish happiness.

What should I do? Am I really in the wrong for entering a poly relationship with my sister's future in-laws?