Did she ask you to change the baby? Did you mention the baby needed changing? Did this sound like some sort of reproach to her?
When you go about changing a baby, the first thing you should do is make sure you have the clean nappy, the bottom ointment if any is to be used, and the wipes all right there next to you. If you had been changing nappies for 9 months, you would know that, and you wouldn't have needed an assistant to find the wipes and then pass them to you. If you had been changing nappies for 9 days you would know that you would need everything to hand first, and not after the baby changing starts.
On the issue of co-sleeping vs. sleeping in the cot -- the baby's cot is in the room only a few feet from the bed, so if the baby wakes in the night you're both going to be woken. You say you know the benefits of co-sleeping, but you seem to be assuming that it is contributing to the baby's wakefulness, which may or may not be the case. Babies' sleeping patterns are never static. Your baby may have slept like a dream baby from day one, and now for reasons of her own has decided to wake 8 times a night, a fact that may be completely unrelated to the co-sleeping. Also, your ideas about co-sleeping come across as 'book-knowledge' rather than an understanding of what it may have meant to your wife, emotionally, to have the baby cuddled up next to her. And you are still coming across as 'the person who knows best' here.
OK, if what you report of the exchange is true, and she really did throw the wipes at you and order you out of the flat, why do you characterise it as 'unreasonableness'? This is what might be expected in a case of PND, which is not 'unreasonable' but a mental illness. You are falling over yourself trying to portray her as unresonable here, Lostboy. You sound like someone who is building a case against someone, not a man who loves his wife.