Sorry in advanced for the long post.
So a few weeks ago my future mother-in-law visited for a ladies lunch and got to have a tour of our venue. While to make a long story short while on the tour she saw the bridal suite and decided that this was going to be "her room" and booked it a few days later as she texted me and said rooms are booked. She said it would give a place for grandchildren to hang out if they get bored at the reception and need a break and she is staying for several nights. She has offered to pay for our room the night of the wedding, an ordinary suite down the hall. So basically our wedding night she will have the bridal suite and my fiance and I a regular guest room. My grandmother and mother where in shock when she announced this, but kept their mouths shut when she announced "this room is mine!". I briefly talked to my fiance about it and he said well it's just one night for us and all the rooms are pretty. He said he understood her want for a place for a "grandchildren hang out" and didn't want to argue and deal with her wrath at the time as we are dealing with moving and changes in jobs etc and would handle it later. I didn't want to push the argument at the time as she was still around as well. Now that it has been a few weeks I have been thinking about it, told one of my bridesmaids about it who is also shocked and my grandmother brought it up to me tonight. I know it is wrong, but I don't want World War 3 but to be honest I am hurt!:( My FMIL is known to be selfish and we have had to stand up to her several times already about our wedding but this is just too far! What should I do?