If you do what you are supposed to do, then you won't have to tell lies, and you won't end up doing something you'll regret. Like when it says "It's hard to imagine But one day you'll end up like me" It might be talking about like she did something she regrets, and went to jail, or started drugs. And when it says "If I stay, it won't be long Till I'm burning on the inside" It could be talking about, if he keeps doing what he's doing now, then he'll metaphorically burn himself from the inside. And when it says "If I go I can only hope That I make it to the other side. " It could mean, that even if he decides to change, he isn't in total control anymore, so he could end up making it worse, once again maybe refering to drug addiction of some sort.