Frizz I have a feeling that this may belong in the Friends & Family section, but let me just say my heart breaks for you.
Is your dad leaving you with her?
No matter what the out come of this is I highly reccommend you go to alateen or alanon to help you cope with this.
I also would suggest you talk to your dad and let him know that you do not want to stay with her without him around.
Talk to your school counselor, this is not something you should be dealing with alone.