Okay, the big, flashing warning sign here is “From what he does to me in the bedroom…”
First, you shouldn’t need to speculate about why your guy does what he does to you. If he’s doing things that confuse, hurt, or upset you, then you should be asking him about it. And if it’s a premeditated behavior, then he should be talking to you about it in advance. It’s very possible he’s a sadist, but he could also be a clumsy, clueless dumbass, or a thoughtless, self-centered shitstain… whatever the case, there is absolutely no reason for you to be guessing. Get some answers.
Second, if his intent is inflicting what you consider significant pain, and he’s never discussed the subject at all, then I can narrow things down for you: jump straight to shitstain. It doesn’t matter if he’s a sadist or not… he’s a problem child. Show him your taillights.
Third, I can’t judge your boyfriend’s destructive capacities at this distance, but a sadist-in-general is no more dangerous than any other man with an erection. (Which, admittedly, isn’t much of an endorsement.) They become uniquely dangerous when they’re uncommunicative, mercurial, or emotionally stunted. (Or plain ol’ nihilists.)
Fourth, sadists can definitely have normal relationships… with masochists and submissives. They can have relationships with vanilla women too, of course, but those would obviously involve one or both parties making huge compromises to their individual comfort and satisfaction, which wouldn’t make much sense when talking about a “new bf”.