I thought her lawyer was in court and said she wouldnt be testifying?
IMO
Yes, he was... There are two parts to the whole spouse thing, the privilege of marital communication (meaning anything said or written to your spouse in confidence) can be envoked by either spouse. The spousal testimony privilege (the right to refuse to give
any testimony in a case where your spouse is the defendant) can only be claimed by the spouse who is being asked to testify.
The first part survives the divorce, meaning a defendant can refuse to allow a divorced spouse to testify about things that were said/written during the marriage, but the second part doesn't, i.e. you can't refuse to give testimony about events that occurred or things you saw if you and the defendant are now divorced.
In this case, Cesar claimed his right to exclude marital communication, meaning Christina was not allowed to testify about anything he told her, or wrote to her in confidence. BUT, and it's a big but, he couldn't stop her from testifying about other things related to the case if she so chose (i.e. Her whereabouts on the night of the 14th, her run in with Maria, whether she noticed the car at their house etc.) She's the one who chose to claim the spousal testimony privilege, which is what you saw when her lawyer was in court.
By not divorcing him, she guaranteed that she wouldn't have to testify at all during this trial. Had she been forced to give her testimony, she still could have claimed the 5th if any of her answers would have been self incriminating, and while that would have been good for his defense (reasonable doubt) it would have been a bad thing for her, from a legal perspective, which is why I said that not divorcing him was probably more beneficial to her than to him.
I'm pretty sure the DA expected him to block any testimony about communications, but I have a sneaking suspicion they thought (or at least hoped) she'd cooperate, and at least give
some testimony. Otherwise I doubt they would have subpoenaed her.