Maybe having a heart to heart conversation with him could really help.

Does he know clearly how much it hurts you when he jokes about your relationship with your ex gf?
Does he know how badly you want things to work out with him?

Maybe just asking him to sit down and listen to you for 10 mins and pouring out your heart to him will give him a better appreciation of who you are and how much patience and support you need from him will make a good change in your relationship with him.