More lyric interpretation:
"The amount of pills I'm taking, counteracts the booze I'm drinking, And this vanity I'm breaking lets me live my life like this" - He's doing many things at once. The "vanity" could have a double meaning, literally it's a piece of furniture but it could also indicate how self-absorbed he is.
"And you can cry all you want to, I don't care how much." - He doesn't care how much she cries and begs him to stop using drugs, he won't stop so she might as well give up.
Rhiannon - Manchester, England, for above 2