Others might disagree, but I think that could have easily happened with someone who wasn't an addict.
Rejection is a complete heartache, no doubt about it, and I've been in those relationships where the truth has been different to the reality being portrayed, one minute things are great, the next a relationship is over.
I would guarantee there is nothing wrong with you, our knee jerk reaction in breakups is to blame ourselves, and we always look for those reasons that will help us understand the WHY of the situation, but again we may never know the answers in some breakups.
As with any breakup it'll take time, you hurt now, a painful hurt that makes you want to hide under the bedcovers for a week and face no one, but that will ease, it's only temporary.
I personally detest breakups, more questions are uncovered than there are answers, and somehow we have to struggle on, and you will, you'll move on in time!!