Welcome back Bonecracker. Your story sounds very similar to most of ours - being stuck in a cycle of using/remorse/using/remorse rinse/repeat.
As Carl suggests, you likely need to consider some kind of formal recovery plan so that you can first quit and then work on dealing with the underlying issues. Recovery from addiction is a lot more than just stopping the drugs/drinking.
Have you ever been to a recovery meeting or considered meeting with a recovery counselor?