You're obviously going out of your way to misinterpret my words.
You came here asking if you should ignore his drug use.
No one has said a word that has changed your opinion. You already decided to let him tell you lies to ignore his drug use, then defend him when it's called to your attention.
In for a penny, in for a pound....what does it matter if he's lied to you once, twice or a hundred times about his drug use?
You contradict yourself because....well hell, why should I explain that in the same post you say the exact opposite thing. You can read.
As has been said, you are 20. He's 23 or 24. The people who have responded to you are all older, more experienced in the ways of the world, and have been there, done that.
I don't say you are young as an insult. You must learn as everyone does, through experience.
You simply don't like what you are hearing from most of us.
So go do what you want with this guy. It's your life.