Families at war already, really scared and worried

My fiancée and I have been together 18 months, engaged since August and she is 6 months pregnant, and Today we moved into our first place together (Its only a flat, but that's all two hard working 24 year olds can afford to rent nowadays!!). Things were going fine, until this afternoon. For some reason, my partner (who suffers badly from anxiety and depression) got really angry and started snapping at everyone for no real reason. Then everyone got very ''tetchy'' and our mums made digs at each other, which ended in her mum getting really upset and going home with my partner. My mum is now getting angry with me for defending my partner, saying that she is taking over and that she is using me, and she apparently told my fiancée that she needs to let me do what I want aswell and stop being in charge of me etc. What I'm trying to say, is my mum has really upset her mum, her mum has really upset my mum, these in turn have really upset me and my partner, and even my gran has been upset by my partner as she apparently ''didn't appreciate the furniture she bought us and told her its not good enough'' but I never heard her say this. I'm really worried about whats going to happen. I hate all this, I cant cope if the families are going to be at war before we even settle in our flat! Mum has said she is no longer going to help us move in and ''doesn't want to come to the wedding next year''. I'm heart broken!!