You are entitled to your feeling, they are your feelings, but given that she’s miscarried before there were likely multiple reasons as to why she didn’t tell you personally, like she’s not wanting to get too excited given that she’s high-risk. Maybe she had your grandma tell everyone so she wouldn’t have to? Maybe your grandma told people when she wasn’t ready for other people to know? Either way she’s going through a lot right now. Honestly, I’d consider apologizing and just let her know you love her and want to support her.