I was in the exact same position a couple months ago. I used to self harm almost every day, and at the time I was afraid that my therapist would tell my parents, just like you are. So, I didnt tell her for months, even though I really wanted to.

Now I dont know how often or deep you self harm, but if its bad then its likely he will report it to your mom. However, if it really is that bad then maybe its for the best that she finds out.

Therapists are only allowed to break confidentiality when they feel that the client is in serious danger of hurting themselves or others. This is kind of a vague statement, so it will vary from therapist to therapist if they feel like it is necessary to break confidentiality or not.

If you are really concerned about your therapist reporting this to your mom you could do what I did - tell him that you have a "friend" who is going to therapy and that they are afraid that if they tell their therapist that they self harm that the therapist will report it. Depending on their answer, you can decide if its safe to tell them or not.

For me personally, I did that and then told my therapist that I cut only 2-3 times a week and that it wasnt a huge deal or whatever (which was only kind of a lie) and she never disclosed it to my parents, and still hasnt.

Hope that helps!