Its hard to tell if that was a rape or not. Alcohol makes people do things they normally wouldn't. It impairs higher reasoning abilities/communication and allows animal instincts to come to the fore. You could chalk it up to him being drunk or maybe its part of a larger pattern. I will let you be the judge. Anal sex has a sadomasochistic component to it. For the giver it is extreme pleasure and for the receiver it hurts generally. Any meaningful relationship- sexual or otherwise - should be based on mutual love and understanding - not sadomasochism. My advice would be to avoid excessive amounts of alcohol. A drink or two here and there is fine but try not to overdo it. Also be sure to tell your boyfriend what you do like and don't like in the bedroom. As a guy I can tell you he WILL listen. If he doesn't then you need to get out of the relationship for sure.