What do you do if the last time you visited your dad you got drunk with your stepbrother and his friend and your mom wants you to see a doctor to check if you were violated but you don't want to go?

Your mother is right. In fact, if your "dad" should be making sure that you have a little more supervision to see to it that those kinds of things don't happen again. It was very irresponsible of him to not take care of you. Your mother seems to be doing the responsible thing, perhaps you should too. It appears you are very young and inexperienced and obviously embarrassed and frightened. I agree with the above poster and also that your mother is being responsible for your safety. If you were violated you could pick up sexually transmitted diseases and it's just not pregnancy that is the worry. Don't be frightened to get the examination. Once in the doctors office (hopefully a woman) just express your views. The examination will be done with great care and they will know for sure one way or the other if you were violated without too much of an internal exam.