Anytime a woman says no, the sex is non consensual. The idea of him telling you that you were "practicing " on him is a lot of rubbish. At age 15.you are not responsible. Even if it were "consensual" on your part it would still be statutory rape, since he was under 18

I had something somewhat similar happen when I was 14. The guy was my brother's friend who was 21 at the time. I didn't want to do it but he of forced me into it. Tying me to the bed and raping me. When I was crying afterward he kept telling me that he was making me into a real woman. A lot or rubbish that has cause me all kinds of emotional heartache since.

Because someone older and more powerful conned you into something doesn't change the facts.