So the question is, what do you do now?
You said you couldn't take matters into your own hands, but I think you can.
When the party camps for the night and the disruptive character goes to sleep, the rest of the characters administer a brutal beatdown. No punches are pulled, and the disruptive character takes damage as normal. Make sure to hit her in the head first so she's unconscious for most of it. Then go into the next dungeon with her at a few hit points. Let the monsters take care of the rest. Meet any revenge attempts with lethal force.
If the behavior persists, administer a second beatdown and then take all the disruptive character's stuff. Leave her a slip or something. Throw all her stuff into the next deep body of water you see. Then go into the next dungeon and let the monsters finish her off. If the player says anything, reply with "We were cool until you kept disrupting the game. You could always knock it off if you want."
Finally, just have the party beat the offending character within an inch of her life, take her stuff, and leave her somewhere tied to a tree with a sack on her head while the rest of the characters head off to parts unknown. Then tell the DM, that player needs to make another character, because she would never find you again and because the party will attack on sight if she does.
Talk to the other players and come to an agreement that the disruptive player changes his or her behavior, or the game needs to take a break for a few weeks. Reconvene and don't invite the disruptive player.
I suppose that's not very uplifting, but this player is wrecking the game for the rest of you and that's just inconsiderate.
Support for this approach
The OP did say,
A lot of us have been trying to talk her out of her actions but she
continues to persist."
And also ...
"...is there anything I could do in game, in character to try and
deal with this potentially destructive player and show her that her
chaotic evil personality is becoming frustrating to the rest of the
He and the other players have already tried talking to her about her behavior. The DM has tried showing the player that her destructive actions aren't getting her anywhere, but she just keeps going with it.
I'm sure the disruptive player knows she's bothering everybody, but since she keeps going with it she apparently doesn't care that she's ruining the game for everyone else.
The OP stated he wanted to know what he could do in character.
D&D characters are usually very violent people. If a character on the team won't listen to reason, clearly understands that they're causing trouble for the others but doesn't care, and causes trouble will most if not all the NPCs they meet, realistically she'd get a dagger in the ribs.
I recommended the beatdowns because they give the offending player a couple of chances to knock it off. The lesson is this: If you're going to make trouble for us in character, we're going to make trouble for you in character. If you stop, we'll stop.
There are quite a few players who think trolling in the gaming session is funny, and they only quit it when there are consequences they really don't like. The only other method I can think of is that the DM take firm control and just tell the player
That didn't happen and the DM's word is final. Knock it off or you
can't keep playing with us.
Unfortunately for the OP, he's not the DM and he's decided that he needs to address it in character since trying to talk it over with the player hasn't worked.
This is an experienced based answer
This answer isn't me being flippant. It's just that I've had to deal with players like this before, and direct unpleasant consequences with the opportunity to let bygones be bygones is usually the only way to deal with them besides kicking them out of the group (which may not be possible in the OP's group).