Pissed off! Ranting

Arianna • With the love of my life and mother to our handsome little boy ❤️
Okay so I'm Greek Orthodox, and my fiancée is Lutheran. I decided that I want our son to be baptized Lutheran. Today we went to his church and talked to a pastor about it. Well my grandmother is very religious. She's also Greek Orthodox. She's just soooo mad that my son isn't going to be Greek Orthodox that she just told me she's not coming to his baptism and neither is my whole side of the family. My mother is no longer with us and my dad works out of town, he's always told me its my child, my decision, and I do whatever I want. I just told him what she just said to me and he told me "it's your child, you do what you want, I'll try my best to be there". My dad is so understanding, why in the hell does my grandma have to be that way??? We also talked to the pastor about getting married soon since we've been engaged for a year and once I told her she told me "what's the point? You're just going to get a divorce". I'm so mad right now. I hung up on her. She basically helped raise me so she's like a mother to me but I'm not going to do whatever she wants because it's mine and my fiancées baby. It was my decision. She won't respect it cause she doesn't get her way. How do I deal with this??? Any advice?