That sort of roughhousing during sex is not okay if you are not okay with it. You need to tell him. I know it makes you feel uncomfortable but #1 your safety and #2 you will grow more and more resentful of the behavior and your sex will become totally toxic spreading to other parts of your relationship. It is best to just get it out there ASAP that you do not like the physical abuse in sex. These certainly are behaviors he learned from porn and standing in as a punching bag is not going to bring you all closer together. Sorry, you must let him know your limits, and he must respect them for you all to have a healthy relationship. I've been there - I didn't handle the best way, I just straight up left the relationship because I didn't want to have the uncomfortable conversation about rough sex. Nevertheless, it is not going to just "stop" it could become more intense and spread out of the bedroom if he infers that you like the domination.