Overeacting?

I just need to vent for a minute because I don't know if I'm overeacting or not. My partner and I rent our own home, it's a brand new home, 2 bedroom, decent size and I love it. He went over to his cousins house today and came home and told me that his cousin (her partner and 3 kids) are looking for a house and he told them that him and I would move in with them. First of all I have no idea why it was not discussed with me first and secondly I told him that I did not want to, we have a baby on the way and I like my own space. We have a perfectly good home of our own so I have no idea why we would be moving all of a sudden. I love his cousin but don't need to be living under the same roof as them. His reasoning behind it was because we would he living in a bigger house but really we would be living with 5 other people and only have one room for the 3 of us. Anyway after I told him my reasoning as to why I didn't want to move he went and told his cousin that were not going to move with them as I don't want to live with her and her family. It's kind of ticked me off because it's another thing that he has gone ahead and made a decision on and when I'm told about it and don't agree with something I look like the bad guy. It's something that happens a lot and it's starting to really tick me off as he never listens to me.I guess I just need to vent because I don't know if it's the pregnancy hormones or what but I'm a little annoyed :(