I really need to sleep. I've had a pretty good rant, so I'll just wrap up for now.
Bottom line was that my feelings were hurt. being a GM is great fun, but you certainly have to put in a lot of work to make it happen. I was up until 6:30am the morning before our very first session. I had just gotten home from a 9 hour work shift before our last session, and played it through before everyone left so I could have an hour or so to nap before going back to work for an all-night shift. A normal person wouldn't have even bothered to set up a session with a schedule like that, but that slot was the best time for everyone else, so I stuck it through and hosted the game for everyone.
So when you quite bluntly hear how people aren't getting what they want out of the game - and quite directly feel all of the passive-aggressive energy behind the statements - it drains on you. Doesn't feel good. I was already very aware that I had to re-balance my campaign a decent amount and was ready and willing to... and then to have someone jump in to tell you what you already know but with a touch of attitude? No, not fun at all.
It's one of those things. Someone complains really viciously that the game is too unbalanced and difficult, so next time they play everyone notices that suddenly everything is a lot easier with magical items coming out of all the orifices. Suddenly it dares to become one of those "There! Are you happy now?!" moments; and then suddenly I feel like the fun gets sucked out.
There's plenty more to this story, but I'll leave that for now. In the end after a great deal of less-than-enjoyable back and forth, all I could say was to ask for patience with a reminder that I am trying what I can. It looks like my players aren't quite as overpowered as I had originally perceived, and can go back to giving them the standard challenge-rated encounters as befit their level. They can go back to breathing easy a little bit more.
Happy players means an ongoing campaign. That's the important thing.
So long that they're happy, right?