I saw a literal demon on my boyfriend's face during a terrifying violent rage, and I don't know what to do
We've been together for almost three years, and our relationship has always been super messy with breaking up and getting back together over and over. Recently, we got back together, and a couple of days ago, I stayed over at his place while his roommate was there in the other bed.
Everything was totally fine in the morning. We were just laughing and watching reels together. I jokingly made fun of his hairline getting pushed back, and in return, he made a nasty comment about my private parts. That pissed me off, so I acted mad. He started trying to apologize super aggressively, which just annoyed me more. When I tried to push his hand off my body, I accidentally slapped him.
He lost it. When I tried to pack my bags to leave, he wouldn't let me go. He threw my bag far away and shoved me hard onto the bed and against the wall until his own knuckles were bleeding. Seeing him bleed made me feel bad, so I calmed him down, put cream on his wounds, and actually believed him when he promised he would never lose his temper like that again.
A little later, while we were getting ready to go out with his roommate, I playfully kicked him in the nuts as a stupid inside joke we always do. He didn't block it this time, and it hit him really hard. He stormed off, came back furious, and started pushing me onto the bed over and over again, even with his friend right there begging him to stop. Since he was being so rough, I slapped him in self-defense. That's when he slapped me back—hard—for the very first time.
After that, I was trapped, completely traumatized, and crying uncontrollably. He took my handkerchief and aggressively rubbed my eyes, acting annoyed that I was crying, and wouldn't let me leave unless I let him punch me in the face first.
Then he forcefully made me lie down on the bed and wouldn't let me get up. Every time I tried to rise, he'd pull me right back down. With his face hovering directly over mine in the dim evening light, I looked at him and got so terrified because I swear I saw a literal demon on his face. It was totally not him at all, since he was never, ever like this before. His face looked completely inhuman and evil, with two pitch-black button eyes and this wide, long, super creepy smiley face stretched across it. It lasted for a while, and it completely froze me with fear. Even he seemed to notice the weird vibe and got scared.
Things just got crazier. He was venting his anger by taking a knife and poking holes in a plastic bottle, and while we were talking, he started placing the knife right against his wrist. Seeing that scared me so bad I genuinely thought I was going to die. He even admitted that if another guy treated his sister the way he was treating me, he would beat that guy up. He finally let me leave just because he thought about his sister, but he still blamed my silly kick for setting off his rage.
I told him I could stop doing those playful jokes, but fights happen in normal relationships—does that mean every single time we argue, he's going to beat me up like this? I am so drained and terrified, and I really need some opinions on what I should do. Is it even possible that some kind of demon or dark entity actually took over him like that?