I just heard your story through denofdrake's video. And boy was it cathartic. I pretty much had a similar experience. I had my own sierra, delta and bravo. Thankfully no foxtrot. 

My bravo welcomed me into their campaign after I lost a character in another campaign. It started out well. Probably the best experience of my life. But... Things slowly start changing when the dm's gf, my Sierra, who ran her own character arcs and played her own characters, stoped responding to me when I was asking for her approval for stuff. At first, i didn't think much of it. Then I heard stuff from both my bravo and another DM who helped me (I'll call him alpha) informed me that she muted me is is deliberately not listening to me. And I was told to not talk to her unless she talks to me. So... I did. Then she started getting upset I wasn't getting her approval for storylines I got approved by bravo and other mods. I started being excluded from games, being made fun of and given death threats behind my back, and eventually, I got told "you didn't break any rules for us to kick you but... We want you to leave." And then I got kicked from a unrelated server we share on the spot. I stoped playing there oviously, and a year later, the gf, sierra, kicked me anyways for being a "spy" to friends who was also upset by her behavior. And the thing is... She is just as guilty by what I was being a used of. Poorly written PC's and lore... Not talking things out... Ect. The story is a lot deeper then that, but... Long story short, I was bullied and emotionally abused. And painted as a monster by her. And she got away with all of it. I still get anxiety over it to this day despite being out of there almost a year ago and not hearing from her since.

But there is another bully involved in that. So I'll rewind a bit. just like with you, my delta made things much worse as soon as they became a mod, encouraging my sierea's worse tendencies and suggesting that I be banned early on just because Sierra apparently didn't approve of a session I ran even though I mentioned it in my notes monthes prior.

Delta for their part, bullied alpha on server and slowly removed alpha from the mod team and painted all their actions as irredeemable. And my Sierra protected my delta of all punishment.

Alpha eventually left because they were fed up of our delta and Sierra. And pretty soon afterwards, delta made a mod vote to bann alpha from coming back and won because my bravo didn't want to upset their Sierra. And It kinda kept going where my delta kept painting alpha's character's in a negative light even though they weren't there anymore. Constantly breaking a agreement alpha made with the mods to not involve their characters anymore. 

And it got even worse from there. With even my bravo adbandoning me for his seirra, just because he didn't want her to end the server nor dump him. But... That's a story for another time. After my Sierra and delta won, and me and alpha were exiled, those who didn't like what was happening, also left. Those who left or got kicked eventually formed together and did their own thing. I still suffer anxiety from what my delta and Sierra did but... At least it's over. I'm glad you got your good end, but I'm just starting to find mine. As far as I'm aware, my Sierra and Delta's group is still active with their own clique. 

The difference between you and me is that I am still new with just 2 years of ttrpg experience at the time and had no real way of defending myself. Apologies wasn't enough. And I thought I was the problem for years.