Yeah, the entire thing was complicated and controversial. If she was fired, I feel bad for her. I think she may have wanted to leave the show, but I think Josh hurt her pride and fired her before she could even make that decision. I don't blame anyone in the situation though. What happened, happened and whatever really went down, we will never know. I just wish Mischa the best in her career and hope that she has much success.
This is the interview where she says she chose for Marissa to die:
YouTube - Mischa Barton killed Marissa