This is a classic fight or flight situation [0] where you are choosing flight.
There is no use being quiet at work. Everyone knows you are a junior so it's ok to act like one. Ask questions. Say "I don't know how to do this. Can you show me?" You'll find that even the "rock stars" don't know everything. It may be hard to ask those questions without feeling discomfort, embarrassment or even anger. Leverage those feelings to ask the hard questions. This might help alleviate some of the suffering you experience after work.
If none of that works then it's time to look for another job.