Please handle this yourself. It is up to you to make the decision about how to deal with that, but think about it now so you will be prepared. If your mom continues to put you in this position, think about your next step in addressing the problem. You may need to get a counselor at school to talk with about the problems at home and to help you learn to cope with the demands placed on you. It is important to stay in touch with your feelings and realize what your role is as the child and what her role is as the parent.
Role reversal is common in families with an alcoholic parent.
Role reversal means that the child takes on many of the parent's responsibilities. This can lead to long term problems for you in your relationships and with your own family and children if not addressed. Since you don't want to do anything to place your sister in threat of harm, you may be forced to care for her at times. However, if you are left alone to care for your sister a lot, it would be important for you to report this to a counselor at school and let them guide you about how to handle that. I hope that helps.