Hello RunAway13: I think you received some great advice from jelly-bean. It sounds to me as though getting away from your family may be a good thing for you. So I'm not saying don't do this. But do plan ahead. Have a plan for what you will do should you & your boyfriend break up, or should his family decide later on they cannot continue to host you. You never know when an illness or accident, or some such thing, could change things dramatically. Likewise, although living with your bf's family seems like a good idea now, it's possible, once you get there, you could find otherwise.
As far as your grandparents & others are concerned, it's lovely of you to think of them in this situation. However, you can't live your life for them. If your family is constantly putting you down & making you feel inferior, this has to have an impact on your self-concept. It is not a healthy environment to be living in, even if you are away at school for part of the year. Just be sure that in trying to get away from your family, you don't put yourself into an even more precarious situation. My best wishes to you.