Being 7 months along maybe she figures it's time to try to reel you back in so she is not alone during the birth of the child. I know with my ex, she once gave me the ultimatum that I had to be with her or I could have no part of the pregnancy or birth. Hopefully your situation is different man! I know you want to be there, and maybe she's opening the door for that to happen even if you two aren't together anymore. Just don't let her pull you back into her destructive web just because of the baby.
I think you are right as my exBPD/npd and her family is all about Image and I'm sure my ex and her family doesn't want people to know she had another kid without the father around, but then again I could see them trying to blame me for abandoning her while pregnant. They cover her behaviors and addiction pretty well so the family doesn't appear to have issues
Ya, that's what I'm currently being accused of! Abandoning her! After ahe accused me of texting other girls, beat the crap out of me, left, and had a new guy 4 days later! And I abandoned HER!
I think the best thing you can do is to make sure your fb post make it look like your happy and getting by just fine without her! Maybe post some of the sonogram pics to show that you are proud to be the father of your upcoming child. But that could backfire if it came to be that it turned out not to be yours as you had expressed your concern about before.