My best advice for you... is to smoke HALF of what you would normally smoke and just FEEL the experience. I think this would restore your confidence in marijuana and when you feel confident (and ready) enough, you can slowly up the dosage without becoming anxious.
EDIT: Oh and very important... look into some relaxation techniques to use while you are high, don't let yourself take that first hit until you're feeling positive. Meditation with binaural beats works WONDERS.