Yes, all good advice above. Try not to glorify this guy and build him up in your mind to being 'the one' for you. You say you were ill matched. Remember that, and don't gloss over it to relive the good times. Think of it as his loss, and know you deserve to be loved truly.
You can't change how he feels, so just try to change how you feel knowing he's moved on. Don't dwell on what might have been, and be glad you were not led along further into the relationship. Time will heal and you will move on too. Good luck