Sorry this was so hard. My own personal opinion is that this right here emphasizes my rule #1 with poly-- the existing relationship needs to be on firm ground for a good long while before adding new people.
I think too often people rush into things because an opportunity pops up, without taking this into consideration. The fact is, that if the existing relationship is on shaky ground, or has been recently and has just barely gotten back to being good, that adding a new relationship is going to be MUCH harder, and may very well end up causing the existing relationship to be lost.
And as you can see, other people then get hurt because they were brought into a situation that wasn't ready for them. NOT to make you feel worse!
I just see this a lot. A relationship barely gets back on it's feet and someone meets someone who gets them giddy and wants to rush into it headfirst without thinking about the potential consequences.
I wouldn't be extra hard on yourself, though I do see this is a potential to take a look and see what exactly was the issue, and what you may be able to do about it. If the fact is that you and the wife hadn't had time to just BE in a relationship and rebuild first-- then maybe you can do that now with the possibility of opening up after you've had that chance to re-bond.