I am so sorry you are going through this. Your post literally made me feel a little ill. I know you must be in a lot of pain right now. Try to hold off on any major decisions until you are more level headed.
The primary/secondary thing is not something I like to begin with, but in your case, I would just find it insulting.
Can you find a sitter for your daughter for a few days so that you can get your head straight. I am willing to bet that family she is suddenly showing the new bf off to will understand when you tell them you need some time.
How is she handling the new beau in relation to your daughter?
Also, it sounds like your gf is very sweet and understanding. If you are poly, you are poly. Unfortunately, it sounds like your wife is not. I would be prepared for how you will react if the new bf doesn't work out and she decides to come back.
LadySFI- me; Pansexual, Heteromantic, Poly. "Open, but not looking".
C-Boyfriend - Pansexual, Heteromantic, Poly. "Open, but not looking".
Courage isn't the absence of fear, but the judgement that something else is more important than fear. -Ambrose Redmoon