worying daughter

im a 15 year old girl going through alot at home right now. Its no secret that my mom has a drinking problem. She drinks till she can barely talk and is slurring her words everynight. Shes extremely depressed and is going through a divorce with my father. Her behavior has beeen so bad recently that 2 of my aunts have sat me down and talked to me because they thought she had been using drugs. She was slurring her words, unbalanced and acting strange and loopy in the middle of the day when there was no alcohol around. Its also very hard to have a conversation with her when she acts like this because she repeats everything twice. This has been going on for awhile now. Its embarrassing to go out to dinner with her beacuse i know shell get extremely drunk. The drinking also changes her behavior. The littlest things set her off and shes been hitting my dad. He even threatened to calll the police if she hit him again. She ignores me most of the time, doesnt even check my grades anymore (which she used to care about alot). i tell her she has a drinking problem and she says "whatever, go to your room." its getting out of control i dont know what to do. She doesnt even do chores around the house and somenights she'll just go to bed withought cooking me or my younger sister dinner. I dont know what to do since my dad is working most nights. Please any advice would help im desperate.