What happens if I tell my therapist that I tried an illegal drug someone gave to me?

Context:

Over 18 (I'm 19)

Went to a rave

Tried E (I just wanted to feel something other than sadness. I was hoping it would make me happy and have a fun time).

After: I had fun with my boyfriend, I called my Roommate to come pick me and my boyfriend up before him (my roommate) and his wife headed to the airport, I then had dinner and finally passed out after more fun.

Note: Never doing it again because it just made me cold, horny, and dizzy.

#Edit: well, it's good to know I won't get in trouble. Thanks for all the responses.

Edit: I'm a dumbass. My roommate and I share the same therapist. **Apparently Aiden (my therapist) will do nothing other than help me.** I am still nervous to bring this up to him this Wednesday, but not as nervous as I was before. I just don't want my parents to find out somehow. I get that I'm an adult now, but they do still terrify me.

Note: We have the same therapist because months before we even made plans for me to move in with him, he recommended Aiden. Then VERY RECENTLY (about two weeks ago) because of my abusive parents, he let me move in with him for my safety. We don't see having the same therapist as an issue because he has been going to therapy for 20+ years and is thinking about stopping his therapy pretty soon.

Edit: Today I have therapy. I am still very nervous. Before I get to talking, I will just recheck the confidentiality rules when I walk in. Again, thanks for all of the responses.

**Last Update: Everything went well.**