***CAUTION: MALE PERSPECTIVE AHEAD***
You and he broke up. It's time to move on. If they feel a connection, don't you think it's somewhat selfish to try and interfere with that, just because you still have feelings?
What I wonder is did you still have feelings for him before you found out that they were connecting? Or could it be that you are rethinking things now that you know someone else is interested?
I'm not making a call on this, you know yourself and the situation better than any one here. But you may really want to look at why it bothers you.
Either way, think back to why it ended. That should help to keep your feelings from flaring.