SB 1536 isn't a "new" law; it passed almost three years ago.
It amended California Code of Civil Procedure §1219(b) to extend what is commonly known as the "Rape Shield Law" to the alleged victims of domestic violence.
"Notwithstanding any other law, no court may imprison or otherwise confine or place in custody the victim of a sexual assault or domestic violence crime for contempt when the contempt consists of refusing to testify concerning that sexual assault or domestic violence crime."
You can simply go to court and tell the judge you don't want to testify. You can also let the defendant's attorney or DA know, if you like; however, you are not required to speak to either side if you don't want to.