For whatever it's worth, what you experienced is common in retail (fast food, gas stations, grocery stores, etc).

As far as receiving terribly inadequate training and be expected to perform amazingly after like 2 days.

As well as far as having managers/supervisors with no people skills or even real management skills (there are some good ones out there, and they are diamonds in the rough, because most managers get thrown to the wolves just like the lower level employees do, so they are about as lost as everyone else, and since turnover is so insanely high, in many cases the managers are not exactly cherry-picked).

Also if you Google things like "retail sucks" and so on, you will find countless stories that echo the same experiences.. crappy training, understaffed chaotic environments, crying on the job and more.

A humorous list: 25 Things You Learn From Working A Crappy Retail Job | Thought Catalog

"24. If you don’t smoke before you start working a customer service job, you will probably start. “A crying in the bathroom break” doesn’t have the same ring to it."

So just try to understand that your experiences in retail should not determine your confidence level, because retail is generally a nightmare.