I don’t think that thinking of this as karma will help. You will just continue to beat yourself up. I’m in the same exact position as you are with your ex. I think you are forgetting about your own happiness. You think you are only happy when you receive responses from him and when he doesn’t respond you get upset. You should be happy with or without him. When you decide that you deserve to be treated with love and respect (which you deserve I assume because that’s what you give), then you will be ready to move on. It’s so hard, but after a while you begin to realize that you can still care for the person, but you deserve more than that. Good luck, just keep yourself busy and try to find out what makes you happy.