RULE 1 of playing a bad character: NEVER CROSS THE PARTY. You're evil, not stupid. You understand the long-term value of allies vs. the short-term value of stealing their possessions.
In fact, a token evil teammate can be very valuable to a party - Sometimes you need to make a decision where there is no morally right answer, like when you need to kill innocents to stop a plague from spreading. Or when you need to lie, cheat and steal to get the right information. This is when the goodie-two-shoes are held back by their moral codex, and the anti-hero is free to act.
Quoted for truth. Our party had an evil guy (ex-rogue guild leader, now on the run) who decided to sell his help to the "mission" we were assembled for, in return for safety after we were done.
He was a right gowt, but he supported the party as best as he could without risking his neck too much.
And at one point he came in very handy as he butchered/desecrated the corpses of an "enemy camp" we had hoped to sneak past (but ending up fighting) so as to throw blame on in-fighting amongst the "loosely allied tribes". The whole time my Good character was busy throwing up behind a bush in response to the gore.
It was quite a memorable moment for the party tbh.