Your testimony increases the chances of the state.getting a conviction. You can help stop him from doing to children in the future what he did to you and others. You can take back the control.that he took from
you. It's not a pleasant thing to have to do, but what a sense of empowerment. Why wouldn't you do it? Have you talked to the investigator from the DA's office about your concerns and fears ? They are use to dealing with victims that don't want to testify. If you share why you don't want to testify, they may be able to releave some of your concerns and fears. If they have a center for sexual assualt victims where you live call them. Some places have people that will go with you the day you testify and they are trained.

