The first reason I think you should get help is because if you've read this far, then you've probably tried to stop already - but failed.
Getting some outside help can give the scales a huge push in your favour. I'd guess that your chances of success will be about 6 times greater.
Don't underestimate the power of discussing your difficulties with someone who's friendly, warm, compassionate, interested, knowledgable and skilled. They can help you to make sense of what's happening, and can give you a structured route out of your current difficulties.
Because a they're not wrapped up in your chaos, they can help you to see things more clearly.
There's also a huge power in giving an account of yourself to someone who's a stranger. They're never going to be angry or disappointed with you if you struggle - like your partner or friends may be. Often knowing that you'll be reporting back to someone regularly can help you to contain cravings and relapses.