What you say when you speak to CASA counsellor/advocate, either in person or on the phone, is usually confidential. There are a few exceptions such as if you disclose that another person may hurt you. The counsellor in this case may have to talk to other professionals such as police or child protection about this. Also, if you disclose that you might hurt yourself or someone else, the counsellor may have to talk to other professionals about this.
You can speak with a counsellor/advocate without your parents being informed if the counsellor thinks you are old enough to make that decision. However, the counsellor/advocate would talk with you about what concerns you might have about your parents knowing and would encourage you to seek support from people in your life who care about you.
It can feel really embarrassing and worrying to tell your parents about a sexual assault. This might be because the assault happened in a situation your parents were not aware of. You might have gone to a party and not told them, or you were drinking and you are underage. Sometimes people feel that they will get into trouble from their parents for the stuff they weren't supposed to be doing, rather than be given support for what happened.
What usually happens though is that parents blame themselves because they feel they didn't protect you. They might feel upset with you if you did do something they asked you not to, but their biggest worry is usually about how you are. Just occasionally parents are really angry but counsellors can help deal with that situation.
Because sexual assault can have a big impact on your mood and your state of mind, it can be really helpful for your family to know what happened so they can help you through the difficult times. Sometimes people can feel really angry or depressed after a sexual assault, and your family may notice a big change in you. If they know what has happened it can help them be more supportive when you have ups and downs in your moods.
A counsellor/advocate can be with you while you tell your parents if that is what you want.
In the end, it is important that you have as much control as possible over who you tell. Unless you are very young or not safe, a counsellor/advocate will respect your decision.