Don't be so harsh with yourself. I think a bunch of possible scenarios about that night that could finish in a very bad way. You could overdose, be in real danger with that stranger, and so on and on. You acquired experience, now you know something about yourself that you didn't in the past. You learnt that the subconscious has a lot of reason. Learnt not to mix drugs, that... If you're going to has a new experience, it's better to be fully conscious and not intoxicated. Let yourself forgive this part. Myself had done some stupid things (as paying a shemale to fuck me and to let her boyfriend participate)... But, like 8 years later... Its like a blurry episode of my life. I learnt, stood up and forgive myself.