I have a pretty fucked-up thing of my own doing, that happened out of gross misunderstandings combined with being young. I heavily regret it, and when I realized it, I was trying my best to make up for it, but it's still unforgivable.
My first relationship was amazing, and since it was a girl from a larger and tight-knit familly (middle of 9 children, we were around 15), I spent a lot of time with them and the time with them was the best part of my life so far. But, being pretty close, they playfully insulted each other, with creative insults being basically a norm and a form of affection. It was fun, but it normalized a behavior that doesn't really translate well outside of that group of friends.
I was also at the time really interested in the whole decadence, from Oscar Wilde to Huysmans, Baudelaire, Rimbaut and the bunch, their lifestyle and pose resonated with me. And for my next relationship, at around 19, this led to a pretty awful catastrophe of a relationship. I met someone with similar interests, and we eventually developed a relationship based on exactly that pose. Lots of alcohol, grand gestures, lot of arguing but then making it up. It was theatrical, we were basically imitating relationships as we saw in the likes of Total Eclipse (Verlain vs. Rimbaud, it's... not exactly healthy). We were awfull to eachother, but it was all just a part of a consensual game that sprung from the art we were both so obsessed about. We both are nice, non-confrontional people, I'm sure it didn't stem from some kind of sadistic desire to hurt on anyone's part, the relationships both of us had before and after that attest to that. But we were young, and trying to impress eachother, and we started taking it too far. It basically turned into a full-fledged abusive relationship. Or rather, the nights were like something out of a Wilde's novel, full of absinthe, fighting and make-up sex, and mornings were compensating for it with a loving and caring relationship, but it all started as a consensual game and a pose we both were ok with.
Eventually, it turned out that one side isn't really as ok with it as it seemed. When that realization drawn on me, I was horrified. It was all good fun, we were living the live from the art we so loved, but it was never about seriously hurting or abusing the other one. When I found out, I immediately stopped it and we have tried for the next year to make up for it. It was a loving and caring relationship, we were nice to each other and I was doing my best to make her life better - not because I was trying to make up for it, but because that's how we both do all of our relationships. We were happy for a while, but it didn't last long, because some abuse you can never make up for.
I beat myself over it to this day, that I didn't realize it sooner. We were basically LARPing decadence and somewhere along the way it crossed a line, which one of us didn't notice, and the other didn't speak up until it was too late. We've eventually talked about it years later, and we agreed that it was a young and stupid thing to do. We're on an ok terms now, but it's definitely something I don't want to ever do to anyone again - and I never did.
It works simillarly to an IRC. You have a server, that server can have channels, I think it can even do voice. But, unlike IRC, you can also use your server to talk to people on other servers, similar to how Fediverse works - if I have a server hosted on myserver.com, and someone else has a public room on server otherserver.com, I can either join the room@otherserver.com or message person@otherserver.com, all from my account on myserver.com.
And bridges are basically just bots that run on your own server, and by scraping websites/using API of the service your bridging they create a private room i.e Messenger@myserver.com, with subrooms per chat, and the bot then sends every message it recieves signed into your messenger account to the room, and vice versa - anything you send there will it forward to the real messenger, basically allowing you to chat with people on messenger through your matrix server. Which solves the problem of "Each of my friend is using different messaging service, can I have them all in one app? (The app being Matrix client)".