relationship problems

okay so my boyfriend (of nearly 4 years) has cheated on me 3 times. (I'm almost 19 and he's 20). the last one was about a year ago. yes, I know that's not good but just listen to the whole story. here recently, he's been crazy distant, leaving me on read, not screenshotting selfies (he usually does), opening snapchats and not responding, and standing me up to hang out with his friends (one of which encouraged him to cheat the second time and hooked him up with someone). he accused me of being too clingy and said a normal girl wouldn't care about "immature" stuff like that. I'm scared there's someone else again but when I ask, he says things like "damn, I might as well be cheating if you're gonna accuse me" or "believe what you want." am I totally crazy like he's making me out to be orrrrr??? help 🙃