Hi.
Sounds like you've had enough of this school, but I would urge you not to do anything impulsive--the kind of behavior that can get you expelled can also have legal consequences or affect your permanent school record.
Take a deep breath and think about this for a moment.
You can probably understand your parents' desire to make sure you get a good education--you may even be grateful for getting a good education later on! I'm sure the stress and loneliness you face now, however, does not feel like it's worth it.
Stepping back a bit may help. You've already spoken with your parents directly about this and they refuse to budge. You may be locked in a power struggle and, unfortunately, parents usually win these types of struggles. A compromise or change in approach might help.
Knowing that you care about your education may allow your parents to soften their approach. The next time you discuss this, let them know that your education is important to you, but that you're concerned about achieving a good balance of educational and social development. One affects the other.
Ask them to help you to investigate a school that fits your needs better--perhaps one closer to home oe one that would allow you to visit on the weekends. Another option would be a local private school known for its academic successes.
If your parents refuse to negotiate, you will just have to make the best of it. Whatever boarding school is like, running away is not the answer. Being there may feel rotten, but it will not compare to the stress of fending for yourself with no resources.
For now, try to find like-minded people at your school. There are bound to be some around. You'll recognize them once you open yourself to them.
Take care,