I wouldn't say I was in your ex's position, I was the one dumped. And by issues, I had more issues with myself. I've never had issues with an ex really, I've always had a good 4 months on my own before a new girlfriend. Then again, I've never really been in love until my last relationship, and even during that relationship I kept fighting against it.
I've come to realize that even though my mother has been the best person in my life and my only real parent, she lost her patience with me often struggling as a single parent when I was younger and took her frustrations out on me as the target of her emotional abuse. It's left me with little or no self esteem and although I feel confident out on my own sometimes, I'm really not. I couldn't even take compliments, even when my girlfriend wrote me letters when I was down saying "Why are you like this? You have this and this going for you." I treat my friends like gold, but I'm emotionally abusive to my intimate partners in my life and it's really ****ed up. Losing the last relationship I had was the straw that broke the camel's back and I'm committed to making everything right in my life.
Anyways...YOUR problems. I was just agreeing that you can only do so much but if you aren't getting anywhere because he isn't helping himself, you have to let him be and do his own thing. My ex tried so much to pull me out, but she was also doing it to get the love I used to give her in a selfish sort of way. I didn't want to help myself and she got sick of it and let all this anger build up and let it loose. Sure he still cares about you I'm sure, but his emotions are really running his thoughts and actions right now, hence the calling you and coming to see you but then backing away. You have to before you build up any more anger or hurt than you already did, that is if you really value this relationship and want this to work. My ex didn't she wanted to be happy and I honestly don't blame her. She didn't try to understand though and if you are there to understand, whether it works out or not, it will bring you a long way and is an important skill to have in a relationship partner.
Remember you have to ultimately put yourself up there above this relationship. Do what makes you happy. Being away from him makes you sad right now, but being with him while he isn't working out his problems hurts much worse.