I've been smoking weed for the past 5+ years and it has been my saviour, truely! Sadly, not legal in the UK (which needs to change imo) however, I will do whatever I need to do to keep my thoughts at bay. I've tried anti-depressants and I felt no difference, I've tried therapy and that didn't work either (knew it wouldn't). I'm not the type that likes to discuss my issues to someone else. It constantly made me feel like a burden and pity party and that made me feel even worse just thinking about it.
Although they say weed is not a cure for depression, it certainly can change your emotions (in a really positive way). This is why I think they should legalise it in the UK, it's long overdue! It's relatively affordable (assuming you have average paying job). For example, I could have a terrible day, awful thoughts running through my head and after 10 minutes of a few tokes, those emotions disappear. I'd sit there, feeling slightly detatched from the outside world, I'd listen to music and I'd be in my element and in a better head space. The world I was angry at would no longer be the case. If only it was a forever lasting thing.
I know you said you wanted to feel no emotion, but I don't think there is anything out there that would make you feel completely emotionless. Maybe changing the negative emotions into positive emotions.
Currently on a detox at the moment but when I feel life is getting too much, then I will go back to smoking. I do this on and off and it does help me.