Craziest mother in law. HELP!

I seriously have the craziest mother in law. She is the biggest guilt tripper and uses her mom manipulative skills to try and make my fiancée agree with her by making him feel bad (there are always tears and threats that he's turning his back on his culture involved - they are from Croatia). First of all, I was okay with telling the immediate family about the pregnancy soon after we found out, but I want to wait till the first trimester is done before he tells his hundreds of cousins and million family friends. She harasses him daily about how Croatian people would have announced it by now and I'm being crazy and selfish for making them wait (I'm 10 weeks). What's so wrong with waiting another 3 weeks !?! Secondly, I want to combine our last names after we get married and give the kids both our names (I'm half Spanish and have two last names and want to carry on the tradition of having a name from each parent). She's apparently been crying since we told her and even compared me to a witch who has control over him and is making him forget his culture. Oh and icing on the cake, I'm not baptised and an atheist (which they have known for the last 4.5 years), and she is getting angry at me because I won't get baptised so I can get married in a church. According to her an atheist Canadian doesn't have a religion or culture so I should adopt all of their traditions. I even compromised and agreed to baptise the child because I know it's very important to their culture (otherwise the child isn't protected by god in their eyes). Any advice on how to deal ??