Yeah, it sounds like the environment was not right for you. However, it seems from the way you’re communicating here that the negativity you feel toward barre and the culture surrounding it came from within you, rather than your barre instructors/classmates.
The mirrors are necessary to keep your form in check and it is optional to use them. The instructor can’t be there to correct everyone’s alignment the whole time and working with the wrong alignment can cause serious damage to your body.
There are body types of all kinds in my Barre3 classes and everyone of them are welcomed the in the same manner. I am on the hipp-y, mama pouch side of the spectrum and the diamond on my finger is raw and modestly sized. Never have I felt inadequate because I wasn’t the most lithe or the most decked out in sparkle. There was a time when I would have been, perhaps, buy not since reaching a certain level of maturity and appreciation for myself.
Barre seeks to challenge those who want to be challenged and help you reach the strongest form of you that you can be. With all workouts, you get out of it what you put into it. I have been going three to four times a week for four months now and haven’t lost a pound, but the shape of my body has changed a lot and barre has made me a stronger, more confident trail runner.
I would wager barre benefits all who don’t let insecurities, fear, or envy issues get the best of them first.