VF - I think it is a cop out that she may not realize how prickly she has been. By telling the OP not to contact her, by accusing her of all kinds of things, she knew exactly what she was doing. This is not the case of Ooooops, I made a mistake. This is a case of being abusive to someone who has been nothing but a friend to her. Going will reinforce her treatment was not wrong.
I'm not trying to "cop out" - I'm trying to look at it with an eye to why the OP's pregnant "former friend now demoted to nodding acquaintance" would not realize that she's earned a demotion by her own behavior. Some abrasive people just don't seem to realize how abrasive they really are........and pregnant women don't always realize that they've had personality changes early in the pregnancy.
There has been a lot of discussion about mental illness, divorce, and other things in life that can impact how a friendship changes over time - if the OP wants to let her old friend demonstrate that the friend is ready to start building the friendship anew - it's her choice. If the OP choses to let the old friend stay a nodding acquaintance - it's her choice. But the old friend may not realize that she's sunk that battleship (reference to a game) and keep trying to play by the old "friend" rules instead of the exisiting "acquaintance" rules.
The OP needs to decide how blunt to be in letting the woman know what the current situation is...........and since none of us know the woman, we don't know what HER social skills & such are. She might be Captain Oblivious, she might be General Oblivious, or she might be Eagleeye and notice right away that "something's wrong" on the OP's side but have no idea that her warped behavior the last few months is why. Because she can't "see" her contribution..........for whatever reason.
Yeah - I've had people who insisted that *I* had taken something wrong when I thought our "friendship" had changed due to the way they'd treated me. What had changed was my willingness to lie quietly when I felt myself being walked on.........they didn't think that they were abusing me, they treated almost everyone as a doormat so why did I suddenly have a problem with that?
Or in one case - I just got tired of trying to have a friendship with a weather vane who changed directions with every breeze (yes, I do like metaphors - but I can't think of any other way to describe her).