Hi,
Sorry you're having such a hard time in high school, though if it's any consolation, pretty much everyone hates sophomore year...

You do have a tough decision, and it really is your decision and no one else's. But I think it's good to keep the following in mind:

1) Your leaving this school absolutely wouldn't preclude you from getting a good education. There are a lot of different options for going to college, and even if you end up in a community college or a trade school, you're likely to do well if it matters to you enough. For the most part, education is what you put into it, and even if you wind up doing education online, I'd think you could still work something out. Nonetheless, my old public school had something called "fresh start" for students who were going through serious trauma or had had difficult experiences with school where they only attended school a few days a week and got a lot of personal attention. I don't know if there's anything comparable to that where you are, but maybe you should look into it.

2) Would it actually make you happier to study online? A lot of the people I know who have studied online or been home schooled have disliked it. They felt disconnected and even more isolated than they did in regular school. Now, I don't know your personal circumstances, and maybe this would be the ideal situation in your case, but perhaps you should think of whether it really would be better for you or if you'd just be trading one kind of education you disliked for another.

3) Please do not say you have "no talents or skills." If you're good at school like you say you are, that means that you're a hard worker, are quite intelligent, and are willing to give something your full attention even in spite of a difficult illness. Don't underestimate the importance of these qualities. They're very important, and not everybody has them.

4) I know being a "fish out of water" sucks. I've been there, though for different reasons, and it was more than a little painful. But maybe you're not as alone as you feel you are. Have you talked to your school councilors at all? Have you joined any clubs or orgs that are based on things you like to do? Do you do any after school activities? If not, I'd suggest at least trying all of these things. One of the most common experiences of being a teenager is feeling out of place, being depressed, and hating yourself. Illness or no, most people have felt that way, and if you could find a way to connect with a few kind individuals, you might find that deep down, they're quite insecure themselves and really empathize with you.

No matter what you decide, I really hope it works out for you.