So my mom has had an issue with my older sister and I talking about we would be moving in with our S/O and this morning we were all talking about my brother who is the oldest and still lives at home and his girlfriend and her son have moved in with us. So back to me, my sister was saying how at least one of my moms kids would be leaving the nest and I said uhh actually two and my mom and my sister had a problem and something to say about it, my sister claims that she waited but her and her boyfriend have been together for a little over a year and my boyfriend (fiancé) have been together for a year. I had already told my mom that we were thinking about moving in together and then I told her that we made a decision to move in together. My fiancé says they don’t have a say so in the matter. How should I go about handling this situation?