Is there any one you can talk to? A teacher? A Grandparent/Auntie/Uncle? They could be options. Most schools have some sort of counsellor who is trained to deal with these issues. A school nurse, could probably work also. Other than that, maybe a GP could be an idea, since you have suggested that your mothers actions have led to suicide attempts, I wouldn't exactly call that an over-reaction, as your mother's actions have had a very negative impact on your mental, and probably physical, health.
Teachers and GPs are professionals, and would at least be able to point you in the direction of help.