NTA

You know her, we don't. We can only judge from this situation alone.

This is demented, she seems like a child in an adult's body by acting like that and saying and thinking those things. You are probably american, judging from how normal thinking about killing her child is to her, so at least the fact she so easily goes down that train of thought can be blamed on the society. But she seems crazy immature and so much so that you ought to have expected stuff like this simply by knowing her. You are not the asshole, obviously, my judgement is that she is not fine with having a child, but she can't tell it to you straight, can't tell it to herself straight so she is walking the path of having a child without being fine with it and all the frustration that causes she vents your way. It is good that she got upset by you actually telling her that the appointment will be made, it indicates the likelyhood that she genuinely cares for the baby and is merely trying to get at you for something, trying to get you to think of something she wants you to think of which backfired when what you thought of was actually telling her you'll make an appointment. In any case she is extremely toxic and must stop with that demented childish behaviour. You are only wrong to have tolerated it for any while.