Hon, talk to your teacher. If you must, tell him/her about what you're going through, and see if you can't work something out. I know that not all teachers are this understanding, but I once got out of an entire essay by giving my history teach. a vague description of the troubles I was having with my meds!
I know how horrible it is to be doing poorly in school.

I hate it! And it's even harder to tell your parents, but they need to be there for you right now.
((((((((((((((((((((((Jess)))))))))))))))))))) I know you're going through some incredibly stressful stuff right now, but we're all here for ya.

Keep your head up, and don't be too down on yourself--this is not your fault, and you're doing all you can to help yourself.
always,
~muse