Most Helpful Guy
It can be really difficult in cases like that.
The most useful advice would be to simply move on. Don't let him hurt you any more. Any attempt on your part to talk to him to initiate some kind of closure will just make things worse, and your desire to try and do something else to properly 'end' it will make you susceptible to him popping back up in your life and wanting something from you when he is feeling horny or lonely.
If you really don't think you can move on just through force of will, then you can always do something ritualistic. That can give your mind the sense of closure. Something like writing down all the things you want to say to him, putting it in an envelope addressed to him, and then burning it. Things like that can help your mind feel like it's said what it needs to say, and that the relationship is now over.
Most Helpful Girl
That has happened to me before and I know it sucks. But I would send one last text just to get your feelings out and say what you need to say. I think you will feel a bit better, even if he ignores your message he will surely see it and maybe come to his senses about the whole thing