I'm sorry but i tend to agree with trolls it's selfish, so so selfish.
You've come here for support which is a great starting point but to be honest I agree with others that you seem to think that the problem is that she caught you not that you use drugs in the first place?!
You are risking your lives hugely, do you really want her to be left all alone? And c'mon there must be better things to do with your time and spend your money on?!
This has really brought a tear to my eye. When I was growing up my mum was an alcoholic (different drug I know but a drug nonetheless) which got worse following her divorce from my dad. From the age of 12 right up until I was 20 when she died, I witnessed so much that I really shouldn't have witnessed. Not only that, as a 13, 14, 15, 16 year old I had so much worry in my mind when I should have been kissing boys and going to discos. I cared for her a lot in those years, guided her to bed when she was too drunk, picked her up off the floor and supported her through all her injuries caused by her drinking. I also felt deeply embarassed when I was shown up in front of my school friends.
It wasn't my intention to turn this post into a show about me but I had to share my experience and show you that this is your daughters future if you carry on.
My mum died just 3 weeks before my 21st birthday from her alcoholism and all I have now is a box of keepsakes and huge guilt of spending our last years together almost hating her for what she put me through.
Don't hide your drug use, that's not the problem. You need to STOP