Sister Inlaw problems

My sister inlaw makes it so we can't post anything about baby #2 coming because she'll be mad. We got pregnant before she did with baby #1 and she publicly posted on FB and Instagram how unfair she thought it was we got pregnant before her . They had been trying 2 years . She has PCOS which makes it harder for her to get pregnant and we weren't even trying . She went crazy after we found out and went to many different doctors . She did get pregnant around 5 months after we did . I just felt like first she couldn't be happy for us and now I have to share my pregnancy with her . After both babies were born we kind of just dropped the whole thing because they are cousins . Well she's been publicly posting about how they have been have problems with getting pregnant again . Now we're pregnant with baby #2 again without trying . We finally just told all of our family but we can't  post anything because she still doesn't know . I don't want the same thing to happen again and my inlaws don't want me to tell her . I'll be 4 months in a week and I don't know how much longer I can hide this belly . Which got me thinking .... Why the hell am I hiding anything from her ? Why should I have to arrange my life around this person because she can't be happy for us ? Am I right or wrong ?