How to deal with very difficult partner

Hi everyone. I am a very junior associate and now recently working very often with an extremely difficult partner. There is no mid level between us and the staffing of this group makes it impossible for someone else to take my work. It is not possible to sub in someone else as a junior.

He basically spams my phones with calls all day, will not listen to any boundaries, and has become borderline verbally abusive and aggressive when I ask a simple question (I am very junior and just started this practice so I would not know everything yet). It is hard to work on other partners projects when he gives me an assignment bc he needs so many check ins. He also pulled me on a call to run through every single recent time entry and present strange edits on verb choice and wording that are against everything every partner has told me. I’ve started to stop answering questions and say I’m busy with other people, but now he sends me page long emails of what I have done wrong. He also always sends emails on separate random chains which drives me wild. He is extremely controlling and has the strangest most nonsensical rules for writing and drafting that it’s hard to keep up.

What do I do? I can’t get off this group and the more boundaries I set , the more upset he becomes. I am not a star student associate but I have gotten generally good feedback across the board. But I dread even working on any of his assignments knowing that it will make him add another. Let me know what to do

Author: ilikethe1975alot