I don't think you're worthless at all.
I think a lot of people - good, otherwise smart people - make the mistake of taking up a drink or a drug again and thinking this time will be different.
Often the only difference is things get worse that they did in the past.
Addiction rarely remains static - it almost always progresses if we keep feeding it, regardless of how much sober time we had inbetween.
I should know this - but, forgive me, I read a lot of peoples stories - are you against meeting based approaches like AA NA or SMART or Lifering etc?
Those kinds of things can provide you with another layer of support?
D