oh, honey, this isn't good but not something that can't be fixed. All you have to do is tell your parents the truth or as much of it as you see fit (I wouldn't lie but do they really have to know the whole truth?). Just explain to them if your ex did say anything that she is just upset with you and trying to find ways to keep you here and tell your parents that she is trying to control you and this is one of the reasons you want out of the relationship with her because she is mentally abusive to you. Don't freak out too bad or she will win. stay calm and use your head.
There is no life without freedom, the freedom to be who and what you are.