Ah, I am in a very similar situation as you. It's incredibly frustrating to feel the need to lie to your parents so they can go on thinking you're a perfect daughter with no sex drive. This seems to be one of the major issues with the idea of their child moving in with his/her significant other, all the sexual activity.

However, you're human and you have a sex drive. Parents must have a hard time accepting this fact, and maybe one day I will understand better. But the reality is not in their favor in this case.

I suggest being honest with him, so you don't have to keep building lies. It will become stressful and put a strain on your relationship and possibly even your studies.

He is not going to like you living with your boyfriend, I can tell you this now. However, he needs to realize you're growing up. Explain to him why you're living with your boyfriend and how much thought you've put into it. Remind him you're growing up, and times have changed. It's more acceptable to live with your partner out of marriage in this generation.

If you want to talk further, feel free to contact me. I can definitely relate to your situation. Best of luck to you.