I apologize for the "what they said" post, but I wholeheartedly agree with Mono and YGirl. I want to underline what they said three times. You have rights, and you should be allowed to have a say. If everything you say you need to have in order to be comfortable is being vetoed, something is wrong. At the very least your wife is not fostering an atmosphere of trust.
And OMG, I underline the part about watching out for your child ten times. Responsible poly parenting is much the same as responsible single parenting--would you move in a woman you had never even met? How hard is it on the child if that relationship doesn't work out? And wouldn't you at least make sure your partner could be a decent parent before you put your child in close contact with them? Even a babysitter gets a better interview before you let them watch your kids.