It sounds to me like you just want help with handling emotions, not a devious plot to keep the star-crossed potential lovers apart. Totally reasonable question, IMO.
It makes sense to me that you might feel more jealous now that you aren't involved with this man anymore. When you were with him, you had a relationship with him that it sounds like had its good points, but went wrong. Now that it's over, you no longer have the good points, and it probably stings a little to know someone else is getting a chance to have a better relationship with him that the two of you were able to manage. I get that. Disappointment over not getting X, combined with proximity to someone who is getting X -- that sounds like it would trigger a little envy in many people. There's a thread somewhere here about the difference between envy and jealousy... maybe take a look at that?
Maybe you still have some desire for a relationship with this man. If that's true, you could either pursue another shot with him or decide to live with your emotions, right? Living with your emotions can be hard, and that doesn't make you bad. Are there things you could do to distract yourself from thoughts of these two dating? Are you finding yourself obsessing about it? If so, maybe find some activity you can do every time you think about them: go for a short walk, make a cup of tea, call a friend, do multiplication tables in your head.. anything to reroute your brain.