Tell the truth or protect my family?

Hold on until tomorrow and then tell them EVERYTHING!!!!!!! Obviously it is unsuitable for you to ever go back to your parents house and the Social Services may have take the responsibility if you are below the age of 18. Your grandmother is probably feeling bad for your mum who is her daughter..The most important thing is that you and your sister and any other siblings are SAFE. I would not feel sorry for your parents as they should have treated you better...good luck!!!!!!