Future Mother In Law Problems

I have been engaged for two weeks and I am already having issues with my future mother in law about the wedding planning. She really is trying to be helpful, but she is just making me crazy. My fiance and I decided that we wanted to have the reception at his house. Because we know that their will be a level of inconvenience and cost that they will incur with the wedding at their house(like electricity and such) we have told them that we don’t want them pay for the wedding. Instead, I am spending the last of a small inheritance that I received from my aunt, about $10,000 and then we are going to come up with the rest ourselves.

Now I realize that with it being at his parent’s house that his mother is going to be pretty involved, especially since we live 6 hours away. But she keeps making decisions without us. The first thing she did was ask me if I had any ideas about centerpieces. When I told her I hadn`t had a chance to think about it yet, she told me that she had already bought everything for them, including fake flowers. When I told her that I really wanted to use real flowers, she said it was my day and my decision but she also acted hurt.

Then we started looking at tents. We discussed what we thought we needed and decided on a 40X60 tent. I have an architectural background and actually made a three dimensional computer model of the tent to help assure her everything would fit. She then went to the rental place without our knowledge and signed a contract for a bigger tent, and put down a deposit, which we are supposed to pay her back. I am kind of insulted because she is ultimately spending my money without asking, and she doesn’t trust me when I say that there will be enough room.

I asked my fiance to talk to her, and all he told her she should change the reservation to our names in case we need to change anything and since we will be paying the final bill. Even just this comment resulted in her getting very upset with him. I feel like right now, she already has her vision of what the wedding is going to be, and she is going to get upset any time we don’t agree. I think he needs to actually talk to her and make sure she understands that we welcome her opinions but that she shouldn’t get too attached to any ideas before talking to us and that she certainly shouldn’t be purchasing anything without our consent. I feel like it isn’t my place to have this discussion with her. He thinks she will realize on her own. I don’t want to insult her or hurt her feelings, but I also don’t want to spend the last gift that my aunt gave me on a wedding that isn’t what he and I had envisioned. What should I do?