I'm sorry, but, what was she doing changing a diaper in your house??? If I have a child that needs to be changed before he leaves (and I always have them ready, but there's that odd time they poop in the hall when mom comes) I initiate the conversation... "Just give me a minute, I'll change him for you" Parents don't come into my house past my foyer unless invited. This is my business, it's like being behind the counter in a clothing store to see a peice of jewlery, most people ask first.

Aside from that, I feel bad for her that she will have to find new care and I feel like you're so upset that you may be burning a bridge. It will look like you're terminating because she's pregnant. I'd hate for that "rumour" to follow you around with future clients.

In saying that... it's your business so at the end of the day you need to do what's comfortable for you.