I would start at this. Why is your boss disagreeing?
Your boss might well have a good point. Or you may actually agree overall, but are quibbling over details. Either of these can be helped by taking a step back.
Sometimes your boss might feel the need to save face. That's not something to dismiss -- we've all been there. In which case, look for a way to help them out (without necessarily saying as much).
Other times, your boss might just be a jerk. In which case it's probably time for a new boss.
For further actions, you may consider blocking this person and/or reporting abuse
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I would start at this. Why is your boss disagreeing?
Your boss might well have a good point. Or you may actually agree overall, but are quibbling over details. Either of these can be helped by taking a step back.
Sometimes your boss might feel the need to save face. That's not something to dismiss -- we've all been there. In which case, look for a way to help them out (without necessarily saying as much).
Other times, your boss might just be a jerk. In which case it's probably time for a new boss.