<human>: Me: 25, male,
Her: 24, female
Relationship Length: 1.2 years
Living Arrangements: Share apartment

My GF got caught in a lie yesterday, which wasn't such a big deal, but then she lied about lying and just was totally invested in her original lie and was saying anything and everything to make it seem like she was innocent (her stories were inconsistent, and she was acting super guilty). The original lie was so blatant, it's insulting that she's continuing trying to convince me that she's innocent. The lies straight to my face about not lying were what made me the most upset.  

She has done this in the past, and I've been able to brush it off, but now, it's pretty uncool, and I'm really starting to lose my trust in her.  How can I deal with this situation?  I don't think she's going to stop lying in this particular situation, and I can see this same thing happening in the future (since this has happened in the past).  I'm stuck in a 1 year lease with her, so breaking up would be a difficult thing. 

I pay for 2/3 of the rent, so I'm thinking of making her start paying for 50% because of the way she's been acting.  Because she won't admit to her lies, I want to make her pay for it.

Condense the text into a few key points
<bot>: gf lied to me, lied about lying, I'm upset and don't know what to do with her.