A guy needs some help

I've been seeing a fantastic girl since January, everything was brilliant until about March. She had cheated on me. I possibly should have left the relationship there but I didn't and gave her a second chance. She was at Uni and had some issues with the place she was living in so I offered her to move in with me, big step I know but i felt that we could both be happy with this move. Everything has been great but because she has moved to a new part of the country and she has struggled with trying to get a job and this has put pressure on me to provide and pay bills for both of us. To be honest i'm struggling. She has a P/T job which is just paying for her to go to and from work. Yesterday she came back from her shift and said that there is a works night out on Friday and that she was going to this. Now 2 things came into my mind: 1. Where is the money coming from and 2. I don't know if I trust her as the last time she was out without me was the time she cheated on me. Maybe i'm just been stupid, maybe i'm being oversensitive, I just don't know. Any help would be appreciated :)