That's.... pretty harsh to say the least, I'm sorry about your situation. But first of all, your mom needs to be talked to... I don't know what kind of relationship you have with her, but if you can get her to sit down with you and talk... Then I suggest you bring it up with her, tell her that that's twice your sister has tried to screw both of your lives over. Also that forgiving your sister without any punishment... is not gonna help anything, and that if you really want her to change, both of you should go to a different police officer. Tell him/her about both of your situations, and hopefully get your sister in some sort of rehab. Just throwing it out there; that if your sister has never even looked honestly sorry for anything that she has done, then there's a very likely chance she'll do it again. She needs an interference at this point, and hopefully it shakes her up enough to change.