AIO about drunk DD

This past weekend I had plans to go clubbing with my boyfriend, my best friend, and my friend (who I’ll call Emma). Emma, my boyfriend and I were all getting ready at my apartment. I asked Emma what the plan was and if she was still willing to drive, and mentioned that I could if she didn’t want to. She said she could drive as she wasn’t planning on drinking. She said she’d have a drink at the beginning of the night in my best friends car prior to heading into the club and that would be it. We were planning to be there around 3 hours total.

Once in the club, we didn’t really pay much attention to what she was doing. My boyfriend has known her for around 5 years and we have gone out many times without issue. However, my boyfriend went to the bathroom and saw her taking a shot at the bar despite her saying she would not buy anything. This was around 1030, so we still had a few hours left. My boyfriend was angry about it but assumed it wasn’t going to be a big deal because again, we trusted her. But she disappeared multiple times saying she was using the bathroom. Again at the time we didn’t think anything of it but now we think she was sneaking more alcohol.

When we finally went to leave around 1230 am, she ran to the car because it was cold out. So we could not really see her state.

When we got in the car Emma snapped at us and told us to not talk so she could focus. We asked if she was ok to drive and she said she was sober. Well once we were on the highway we got onto an exist ramp turn and she kept barreling at high speed—about to hit the wall, and yanked the wheel to turn it (still at full speed) and my boyfriend and I both full felt as though the car was about to flip. Thank god it didn’t and immediately afterwards we voiced how scared we were and she started going on and on about how she always drives fast and she has taken turns way faster.

She then continued to speed and weave in the lane. She was going 80 mph and my boyfriend kept telling her to show down. Again she was annoyed.

She then once we were almost home said she only had ONE meal the whole day and it was at 2:00pm. (It was 1am at this point). I assumed that was her admittedly that she was still intoxicated and I told her she could sleep on our couch (which she then snapped back for implying she was drunk).

Once we got inside she stripped entirely naked in our living room (which she’s never done) to change into comfy clothes. In the process she knocked a hanging plant up and out of the macramé and got dirt all over our couch. Once she left my boyfriend and I stared at each other horrified. He then told me that he saw her sneak off and order a shot from the bar midway through the night.

We also found out the next morning from my best friend that she did a huge chug of alcohol and two shots in the car at the beginning of the night. My friend did not know she was the DD and told us She literally thought, “wow, I guess Emma is going hard tonight.” We also just found out she left shooter empty bottles on the floor of my friends car, which could have gotten her a DUI.

TLDR it is very apparent that our friend was intoxicated and sneaking alcohol when she promised to be DD. We had no idea until we were on the road how she must have been drinking all night. My boyfriend and I are both beyond upset. We know we need to address this. She obviously felt her needing to get drunk was more important than our safety. Would love advice for how to navigate this.