I'm sorry, it's so hard when you feel like you've let your child down. Just know that 1. you haven't and 2. We have all been there, or will be there, at some point in this journey called Parenthood.
Is there a lovey you could give him as replacement? It's bed time for me but I'll pop on tomorrow to offer more helpful suggestions. One thing that will help is consistency. I never used PU/PD because my boys hated it so I used Shhh-Pat every time. Just something to think on. You're re-training his expectations from a pacifier to sooth, to himself. It's not an easy task to ask of him, so you have to be gentle, patient and consistent.
Back soon!