Anyone with someone who has kids already?

My boyfriend and I both have one child of our own from past relationships. He wanted to move and get a house down south. And moving from NY to the south was a big change but I went with it. Now I'm pregnant and I can't even show it off in social media or anything cause his sons mother doesn't like me and doesn't know my son and I moved with him. She tells him if she finds out that I'm with him she will never let his son come to visit for the holidays and school breaks. So he wants to hide me until his son comes but he's son had two chances to come and hasn't and if he doesn't come for Christmas than I wait even longer. He tells me I'm being selfish and I shouldn't act like this cause a child's feelings comes first but I understand and want his son to come but what if he doesn't come till next summer than what ? I'm due in May I just hide my baby from my family and friends? I just need help with all this