In need of any kind of help. Very lost.

My gf and I have been hating for 2 years. I used to think we were very happy and nothing could get inbetween us. But about 6 months ago, I found out my girlfriend had done Coke.

( a little background is my mother was an addict and I've told her stories about me being 10 watching my mom snort stuff while driving and nodding out. But my girlfriend and I smoke regularly and trip every so often)

I was very confused when I found out she did coke & a little hurt, but
Not mad. Confused because I've never told her I didn't want her doing it I've just told her my history with it and hoped she understood and she used to tell me how much she hates coke and how she's tried it and doesn't like it, and hurt because she didn't understand.

Anyways when I found out she lied to me until she absolutely had to tell the truth. We lodge fought. I told her she was like my mom while in tears, but finally she got me to calm down and we were okay she promised not to do anything like that again.

Last week I found out she did it again I confronted her and she asked how I found out, I told her her search history. We fought again but again, we are okay. But I can't help but feel scared every time she hangs out with her friends that she's going to do coke. And now if I go to her history it's blank. I'm so lost and hurt.