In your case, since you signed as a surety then the liability cannot be discharged until and unless your father arranges another security. Since the loans were taken on your name, you cannot be a surety so I am assuming that your father has taken loan on all the sisters name by making each other surety for each loan. In such a case, your father here has no role as his name is not surfacing anywhere. However, since your allegation is that your father abused you and forced you to sign on the loans paper, a case against your father can be filed for criminal intimidation, physical abuse, etc. But that needs to be proved by proper evidence, be it oral or by way of physical examination showing the marks of the abuse etc.
As per law, you cannot file any other law suit against your father since the loans are on you or your sisters name and all of you are surety for each other and your father would be given a clean chit by the court if the cases of repaying the loans would be filed against you three sisters.