If you are under 18, call the police. They will come in and see to it that you are put into the care of the proper children's services people. You should not have this dumped on you. Your mother may have done something against the law if any of you are minors. If all of you are, that is really horrible, and you deserve help.
If you are 18 (adult age) you can get help and support from your local Welfare Office, since you are responsible for your siblings right now. If you are underage, seek help at your local Division of Family Services. Both places should be able to direct and help you to cope with what you are going through. Also, some churches will offer to help by donating food, money, and someone to talk to. I pray for you all. Be strong for your siblings, at least long enough to get the help you need. - Blu