Legal Question in Civil Litigation in Arizona

There probably isn't much you can do at this point. If the judgment was just entered you may still be able to move for a new trial, but to win you will have to demonstrate that the testimony was false and explain why you were unable to make such a demonstration during the trial. In other words, you would have to offer evidence that not only wasn't offered a trial but couldn't have been for reasons that are beyond your control. That's a very high standard to meet.

You have the option of filing an appeal (assuming that the deadline hasn't already passed), but appellate courts generally must accept a judge's or jury's factual findings if they were supported by substantial evidence. The roommate's testimony was substantial evidence, even if it was falsified. Arguments about whether to believe particular testimony are not allowed on appeal.

Given the amount of money at stake, I hope you had a lawyer representing you at trial. If you represented yourself, there is a very good chance that you failed to do things a lawyer would have known to do in order to challenge this testimony.