Replying to What would you do in this situation, please be nice

Okay, I finally got out of college for the summer on Thursday.  I was sitting around today and asked my friend Sarah if she wanted to go out tonight.  Last night, I spent 2 hours helping Sarah out talking about her ex boyfriend and she was crying to me on the phone etc.  I pretty much talked her down, and I feel like I helped a lot.  Today, I asked her if she wanted to hang out and she said "I'm just going to stay in for the night".  I thought fine, she just got back last week too so she probably wants to spend time at home.  Well I just called another friend and she said she was out with her too.  So, she lied to me and told me that she was staying in but instead went out with other people and didn't tell me.  All this after I helped her out, and I help her out ALL THE TIME.  ALL THE TIME.  I know NS is filled with a bunch of 15 year old guys, but what would you do in this situation?  Thanks if anyone gives serious answers, and I'll reward you with karma or whatever you want minus sexual favors.