I don’t know how to tell him

So I have been with my bf for almost 6 months and recently I am pretty sure I have lost feelings for him. The last month now has been terrible. We have only been able to see each other a couple times outside of school (in school we can’t be all touchy in any way or else we get in serious trouble). Because of this he has been such an asshole. Snapping at me at random times. Not giving me much loving attention. And only asking me for sexual pleasure over the phone. Then after I say no he would apologize for snapping as if that would change my mind on showing him stuff. I’m at my friends house right now to get away from all my stress of living at home for a few days. And I’m now realizing I don’t have feelings for him like that anymore. I can’t see him as my bf. I feel gross calling him that. I told him this last night and he got mad at me for losing feelings and started gaslighting me. Telling me I havnt lost any feelings cause I still have the necklace he gave me on. How I havnt lost feeling and I won’t lose feelings cause he isn’t gonna let me go that easy. That we are gonna stay together. But I don’t want this. I don’t know what to do. I want to go off and tell him to fuck off. But I don’t think I can. A while back he had convinced me to send him pictures of me...down there after I got back from the hospital. Although I know the truth of them. I doubt anyone else will beleive me if he leaked them. I was still high from the strong sedatives they gave me. I don’t know what to do.