AITAH for breaking off my engagement because my fiancé made an offensive joke about me to his friends?

Buckle up. It's long and I'm sorry about that.

I (28F) and my fiancé (32M) have been together for five years. For the sake of anonymity, I'll be referring to him as John. John and I have had a wonderful and loving relationship for these past five years, and I truly saw myself with him for the rest of my life. We've had our ups and downs, but not once has John ever made me feel like I wasn't enough. He's supported me in all of my endeavors and dreams, and our relationship even survived nine months of being long distance as I'd been sent to another state for work in 2021. I truly love John, and even now, I still love him, but I have my doubts now about how he feels about me.

A little context. I grew up fat. I had been fat when we met and for the first three years of our relationship, I was fat. This isn't a problem and never has been in our relationship, but it was something I had a problem with about myself. I wanted to be healthier and to simply lose the weight because I knew it would make me happier. John was supportive of this. He said he'd love me no matter what form I took because it was my heart and soul he'd fallen for. I had believed that as I had no reason not to. John has always made me feel that he loves me and made me feel desired.

But now, I've lost half of what I weighed before and at my age and due to being overweight my entire life, I have plenty of loose skin. I am absolutely insecure about it, and John knows this. He's made every effort to reassure me that he still finds me beautiful and that he looks at my body as the evidence of how hard I've worked and how far I've come. He reassures me that he still loves being intimate with me and loves my body, even as it's changed. I felt so lucky to have a man who loved me so unconditionally and truly.

Recently, John and I had gone out with a bunch of our friends as we'd not been able to align our schedules until now. Whenever we go out with a big group like this, John and I usually spend the beginning of the evening and the end of the evening together at the party. At some point in the middle, we always split off to go socialize with our friends separately. When it came time that I went to rejoin John, I had seen him with his best friend and a couple others, engaged in conversation. John's back was to me, and his friends were all chuckling about something as I approached, but I stopped dead in my tracks when I heard John tell his best friend that my body looked like a "deflated weather balloon" and that it was hard for him to not laugh when we were intimate and my body moved.

I had never expected the man who spoke so warmly and lovingly to me always to talk about me in such a way. John was the man I was going to spend the rest of my life with. He'd known my insecurities and still loved me anyway. At least, so I thought.

Needless to say, I was hurt and angry and devastated. I walked up to him, handed him his ring without a word and I left. I didn't even go to our home. I went to a hotel and stayed there. I turned off my phone and just took a couple days to just cry out my heartache. When I turned my phone back on, there were messages and voicemails from John and our friends. Most of John's messages were apologetic and begging me to talk and come home. But then the most recent were the opposite. He said I was cruel and cold for ignoring him and breaking off the engagement without warning or so much as an explanation. When I responded to him and told him I'd heard what he'd said, John told me that I was acting like a child because I took his joke too seriously. That he was just trying to make his friend laugh. I asked him why he needed to make his friend laugh at my expense by telling him about my body and how it looked to him or how he struggled not to laugh at me when we were intimate. He didn't respond.

Instead, as I'm writing this, I'm still receiving messages from our friends telling me that he's sorry and that I should "see how miserable he is" without me. That I'm so cold and a bitch for running off like that instead of giving John a chance to explain himself.

I'm hurt. I genuinely don't know if I was too rash in breaking off our engagement, but the only thought in my head and what is still sticking with me now, is that when I was fat, people mocked me because of my body all the time. I lost the weight only to still have people mock me because of my body. And it just so happened to be the one person I allow to see me at my most vulnerable who showed me that. I know John's hurting (or at least seems to be), but so am I. Should I have heard him out? Five years and I didn't even give him the chance to explain or to really apologize. I just shut him out immediately. I still love the man, those feelings don't go away overnight, but... I don't want to hear his apology. I don't want his explanation. I'm just... angry and hurt and my friends seem to think I'm throwing away my relationship over something easily fixable.