Whew. Deep centering breath.
It is obvious you have a lot of stuff going on in your life right now that has spun out of control. As it stands, the very first step is committing to getting yourself to a place where you can re-take control, and make some decisions about how you want to proceed.
First and foremost, it is time to stop huffing, stop the alcohol, and stop the pills. when you spend so much time numb, you can't possibly begin to take the steps you need to in order get your life together. Most people with addiction issues need some sort of outside support to keep them motivated and focused during the process of withdrawl. If you need referrals in your community, we'll see what we can do. However, if you have a doctor, or other trusted adult you can turn to, ask them for ideas. While getting sober isn't easy (mostly because it will force you to confront your feelings while you aren't anesticized) it really does help you regain feelings of control, which will in turn help get you self-esteem and confidence up to a workable level.
With your first committment being to sobriety, your second committment must be to turning attention to the relationship with your mom. It sounds like she probably has her own issues. If you confront her in a non-aggressive way, and tell her that you feel that both she and you need to take steps to repair your relationship, what do you think will happen? Perhaps joint counseling for the both of you would be a great idea. sometimes, when we are 18, it is hard to see things from our parents perspective. Obviously, she probably knows that you aren't sober, and that you are going through some big-time emotional drama, so lashing out might be her way of expressing worry. It isn't necessarily right, or even healthy, but your mom is a person, and she isn't perfect, either. However, if there is real abuse going on, you need to talk to your father frankly, and demand that he get involved. If he refuses, go to the police station, talk to them about what you need to do.
Lastly, since you are 18, you can always move out of your parents home, legally, but that will take a committment to getting a good job that can support you. Perhaps you have friends, (and not the ones you're getting high or drunk with, because new sobriety is pretty fragile, and it is terribly easy to backslide if you don't have a good support network) that have it together enough that you could look at apartment sharing. Perhaps you could even look into the possibility of grants or loans that you could take a class or two at a community college. The structure that formal education provides can be very, very comforting when you've committed to such big life changes.
Certainly, if you have any other questions, or just want to vent, we're always around, and we make a pretty darn good support network, so if you need us, just post.
(the old one who has been there, done that)