My MIL Wants To Go On My Honeymoon!

My FH and I decided that we wanted to go to this local lodge for a couple of days for our honeymoon and he told his mother about it. Today she says that she talked to her daughter and they are planning on staying at the same lodge the same days that we are there. The reason we are taking a two day honeymoon is to get away from our three kids and our families. How can we do that when my MIL will be there and she will have two of my children with her. I know that if she knows that I'm around she will find a reason to leave my kids with me (which I really wouldn't have a problem with if it wasn't my HONEYMOON). We searched all afternoon and there is no place local that we have found that is affordable and that we have liked. Do I have a reason to be upset? My FH stated that we can still go to the lodge but we will hide from his family and that he doesn't want to be bothered by anyone. So I guess we will have to lock ourselves up like hermits and don't enjoy ourselves.