Family issues

Long story...My ex and I don’t get along with his mom .. she chooses to befriend his ex.. won’t even wish him hubby a happy birthday. My mom doesn’t seem open to the idea of me having another child (although I make almost $100k and I’m educated and in a stable, loving marriage, my youngest is 9). We decided not to tell either until 2 days before Facebook announcement. My mom is Hispanic, I’m afraid I’ll hurt her feelings. Does anyone has any tips or advice?