Stopped during sex and my bf is mad

I just stopped my bf in the middle of sex because he was doing some things I told him not to do a few times (they’re kind of triggering for me, I’ve been sexually assaulted). Now he’s mad because I “didn’t let him finish”. To be fair I never properly explained to him why I don’t like those things, only that I don’t want him to do them, so I think he’s a bit confused and might think it’s something wrong with him. Am I in the wrong here? 😣