<human>: Give me the gist of the text in a nutshell

Hi All,

I need some advice regarding my current relationship. I've been with my GF for almost 4 years and we've been living together for 3 years now. We're both 24 and everything was fine until this summer. We were finally reaching the same point in our life where I was done with college as of 3 years ago and she just finished college. I was waiting for this moment where we'd both be ready to move to something else professionally and personally speaking. We had plans of moving out of town to the other side of the country to try something new, buying a house, traveling, etc.

Now this is where things slipped, she went back for her summer job to the same place she was last year which is a bit of a trashy place where most people have no education, lot of people into drugs, etc. She started hanging more and more with people from there to the point where she started smoking every day, Driving Under influence, started taking harder drugs on week-end (Speed, cocaine, etc.) and being very defensive when I try to get her to calm down a little. She's now telling me that she's not happy with a regular 8 to 5 routine and it's not the life she wants. She was always someone with a lob of ambition with a normal life and who even judged those type of behaviors and it's almost like it all went down the drain within a few weeks

This all came out of nowhere so fast and I don't know what to do anymore, I know how she reacts when somebody try to talk her out of something and she starts lying and doing the exact opposite so I feel like my couple is slipping out of hands at an alarming rate…what am I supposed to do at this point? Her summer job is ending soon so I'm hoping the dust will settle afterward but I'm freaking out right now…
<bot>: Girlfriend changed completly within 2 months and I'm losing her. I don't know how to deal with the situation...