I know this might sound overly simplistic, but it really seems like a question of drive.
Every career, regardless of where, who, when, and how its performed -- will have naysayers, backstabbers, and obstacles. The only reason that anyone stays with the career they have is that they recognize the above and STILL want to do it.
If you can look at all the adversity that you'll face, all the backstabbers you'll meet, all the harsh competition... and still want to do it? You're set. That's all you need.
I'd extend this to any action: if you know ALL the potential consequences of an action and you still want to do said action - then you'll only regret it if you don't do it.
And I wouldn't worry so much about being on the street with a drinking problem and a broken spirit. You've got support, here, in your fiancee, and in other people.. that's half the battle. The other half is wanting to do it. Even if acting COMPLETELY falls through, you'll only fail if you give up.
My vote? Do it.
