Good for you fessing up to your short comings as you see it. That is very brave. It seems that you need more bravery and more fessing up however....
This is thread that might help with the term "cowboy."
It doesn't seem to me that you are a cowboy by the regular descriptions in poly theory. I would say you are a "cheater." With a cheater mindset. I have been one also and it took years to re-train my head.
It takes years to get through the entitlement one learns to take on when one cheats. Its almost as if no one else exists. The concept of being considerate/empathetic/compassionate seems to have to be re-learned. It sounds to me like you have not learned this yet. So start now. Every time you find yourself in desire of what YOU want, ask yourself what would occur if you acted on that. How would your wife feel about it, how would your gf feel, what would the possible scenario unfold if you were to "go there?"
I would suggest that if you have one ounce of doubt about what you are doing, either don't do it and relay the circumstance later to those involved and check if your gut was right, or ask. Make a phone call and check it out. Don't assume anything and don't expect others to be willing to just bend because you want them to. If they say that in no way would they be okay with what you are asking, then don't do it. Walk away.
I would suggest asking your wife for help on this. You seem to be unable to do it alone. You will likely have to make yourself very vulnerable to her and others, but in that, you might be able to re-build your integrity in her eyes so that she can trust you again. You will have to work hard to get to a point where YOU trust yourself again.