My opinion: Tell your roommate exactly what you know so she won't think she pulled one over on you and got away with it. She's dishonest. If she believes she got away with this, she'll be encouraged to do more dishonest actions. She stole $200 from you! In addition to that, she took other things that are above monetary value. One of those is your trust in her and probably in other people in general. Last, but not least, get a different roommate as soon as opportunity allows.