My [F35] boss [M51] favorizes my coworker [42] over me

I've known my boss for 1 year. He's known my coworker for 10 years, altough they have not worked together all this time, just 3 years. We're lawyers. I was recruited, he brought her to our law firm. No, he's not a partner.

She's kind of a boss bitch. She likes to talk badly about people, how her other coworkers were always stupid and dumb, how she was always the smart one, etc. She sees herself as know-it-all and YES, she does have more experience and knowledge than me.

When I texted him we're heading to a client tomorrow morning, she said 'well okay, if YOU informed him, that's FIIIINE...' as if only she can report to him, being the senior one.

Anytime we're working on a case together, she always wants to get her way - even in completely irrelevant things. I always change them as she wishes, but I'm frankly tired - I'm not her little assistant and it honestly doesn't matter whether we formulate it THIS way or ANOTHER way - meaning is just the same.

Once when I explained sth, my boss disagreed. Then she said the exact same thing in another wording. He said only NOW he understands and agreed.

I cannot change my workplace, at least not for now.

How do I act? I cannot be her little bitch anymore and I'm sad my boss decided to go this way. It seems like I cannot do anything independently - even inform him about how's the work.

On top of that she often lies to him when she's leaving the work earlier - she loggs in from the bus when she doesn't want to get late or she leaves earlier and loggs out from the bus on Teams.

When she was 40 min late to a meeting with a client, he said nothing. I artive 5 min late and I'm having a talk with him.

Yes she is more experienced, but not THAT more experienced and when she corrects me, it's ALWAYS just different wording of the same damn thing. This is law - you can formulate same thing many ways.

She already had an issue with 3 other coworkers, 1 of which turned into a fight in the client's office - quite embarrassing. 2 of these coworkers don't work anymore. My boss took her side.

PS - no, they don't have a romance, my boss is just kind of a p.y who likes to be bossed around, apparently.

I don't want to give her this satisfaction and leave.