Idiot.
Now that we have that out of the way, what you need to do is realize that reason you can't shake the past relationship is that you keep feeding the feelings, memories, etc. You are in a pretty messed up situation that won't get better because you decide to duck out. You want advice. Here it is; it's worth what you paid for it.
Give some long hard thought to whether you are going to honor your marriage and commitments.
Then commit yourself to that and discuss with your wife.
If you decide to go active I would only do it
1) with your wife's agreement and support, after discussing and clearing the air.
2) as a way to remove yourself from the present situation if you think you can't handle any temptations until you get this out of your system.
3) if it doesn't prevent you from meeting your obligations to your daughter, for example, if she'd be better off with you around to intervene, stay there and do it.
Good luck and keep us posted.