Hi there. I'm sorry that you are hurting but you are an adult. As an adult, you make your own decisions. Some will turn out good and others bad but they are your decisions. If you want to be with your girl friend than be with your girl friend. You may need to move out but the both of you should be able to make it. If your parrents decide to disown you, that is their decision not yours. If you want them in your life, tell them that the door is always open if they change their minds. There is no need to be unhappy or scared. Make the decision and stand by it. This is only a suggestion and it is not my decision but yours. I hope this helps.
You are in control and you have to do what makes you secure and happy.