I don’t believe that the OP would be confessing the boss’s sins. The OP would be explaining the circumstance in which he was brought to be rebellious and disobedient.
For you to advise the OP to not mention the boss would be like a confession in which someone shot and killed a man, without explaining that the man approached making menancing words and gestures. It changes the picture completely.
The OP is not confessing the boss’s sins, He would be describing the circumstances in which the OP found himself which precipitated his action of sin. If the priest found this information to be an excuse, then that is exactly what the OP needs to know. On the other hand, if the priest found this to be a mitigating circumstance, the OP needs to know this as well.
This is the kind of thing the priest needs to know that will help him give spiritual guidance to the person confessing, to avoid this sin in the future.