Try out Gamblers Anonymous, it might be useful. Or some form of spiritual/religious group or pathway. Saturate yourself with positive/spiritual energies and it'll cure you of everything
The addiction is to the "high" you get when you win, especially if it's big like Peleke said. That euphoria, joy, thrill, etc. gets automatically conditioned in your mind, and you keep trying and trying to get it back. Add that on to the wild emotional swings of losing and winning, losing and winning, and you get addiction.
The way out? The willingness to surrender the pleasure you get out of the experience. The pleasure you get out of winning, the pleasure you get out of gambling, even the pleasure you get out of losing and wallowing in self-pity.
Of course, don't go back to gambling to surrender it, just imagine the situation in your mind, and start letting the emotions run themselves out. Don't indulge in the pleasure. You'll notice your mind trying to "juice" it, wanting to experience the pleasure of it, but don't let yourself get suckered into it
It's kind of like deprogramming the Pavlovian conditioning of it.
I like Peleke's solution too: reminding yourself of the negative aspects. And whenever you think of the positive ones (which are illusory, as you know by now), surrender the emotional pleasure you get out of them immediately. Just stay focused on your awareness of it, detach from the emotion, and just let it keep running itself out. Don't suppress the emotions, but witness it, and let go experiencing them. Stay on the crest of the wave of awareness, and keep letting it go. Sooner or later, all the emotional energy gets processed out, and you're free as a bird