I got black out drunk for the first time… Ever

So I’ve been drinking everyday for the last month and a half. Roughly half a liter. Never have I blacked out ever. Everyone else around me would say they didn’t remember wha happened the next day but I’d be able to recall perfect detail. Yesterday at 3pm, I took 5mg of diazapam. At 8 I started drinking. Bam. By like 11 I was flat out apparently. Woke up 9 hours later with my friend saying she said I looked peaceful, but she has to check I was still alive. I didn’t even do that much alcohol.

WTF?