<human>: Could you distill the essence of the text into 1-3 sentences?

Hey.

Me and my girlfriend just had a quite a big argument. After work (~1am) she smokes weed, and then drives home. She says that the chances of her getting into an accident is so small it is not a problem, and that the weed doesn't effect her driving too much. In my opinion, which I made clear, driving under any any influence is wrong, immature and a bad decision. I told her that even in an innocent accident (someone elses fault), having a DUI or similar on her record would be really bad, and not worth the small high that she describes. As the argument got more heated, I told her that how she talks about this issue and her actions make me think less of her.

This really upset her. 

I think what makes it tough is the fact that I don't want to apologise, I *do* think less of her in this regard. Should I anyway? Is there a way I can put this another way which makes it sound less.. offensive? Was I out of line for saying this? I'm really not sure. Any guidance would be appreciated, this is new to me and i'm not sure how to navigate it. I'm just struggling with the fact that she's obviously an adult and can make her own choices, am I out of line?

Thanks
<bot>: Girlfriend smokes weed and drives home. I told her that i think less of her because of this. She's really upset, did I cross the line? Do I have a right to feel this way?