In your case it is not too late. It is not too late in anybody's case. Start by losing the self-pity thing. If you have learned anything from the arts, the music you listen to, the books you read, the movies you watch it is that all of us have doubts, anxieties and insecurities. You think yours are more extreme or more special, they are not. Get over yourself.
To aid in losing the self-pity you need to make an act of will and to be temperate. No intoxication for you. Not for some time at least. Start with a second, a minute, a day. Each is a victory you can build upon, an achievement, and achievement begets achievement. (BTW taking a step back is not utter failure condemning you to the bowels of oblivion, it is simply not an achievement, get back on the achievement train the very next moment.) Will is like a muscle, you develop it by exercising it, first in small matters and then increasingly.
Practice honesty. It is disarming since it is rare (Not brutal honesty, just honesty). You will also not be exhausted from trying to remember your lies.
This is a start, this readily dismissed drug store advice. If you actually take it you would be well started on the path to change and healing by Labor Day. If not, if you chose in your own comfortable self-indulgence to revert to your self destructive patterns come Labor Day we will simple have gone around your cycle yet again.