Rude

Last night I got a message from my fiance's "aunt" (she is actually just a good friend of my fmil) that she can no longer attend our wedding which is 10 days away. We are now having to pay for her to attend because we have a minimum on food and beverage and if we don't include her in our count then we will be under budget. It annoys me that we have to pay for someone that let us know last minute that her plans have changed. Her reasoning was that there is a problem she has to deal with that weekend which seems very strange to me. I already thought it was strange that her husband wasn't attending even though he was invited. I'm not sure I believe that she actually has a problem to deal with. Normally if there is a problem you don't wait to deal with it until 10 days later. I think something else came up that she would rather do. She also didn't tell my fmil which is also strange to me since they are really good friends. My fiance didn't care to invite her when we first started making our guest list, but my fmil insisted on us inviting her so honestly I think my fmil should pay for her friend that isn't attending since she wanted us to invite her. I told her she let us know last minute and she basically said oh well. My fmil's other friend might also be a last minute no show, but her reasoning is much more understandable. Her daughter-in-law is fighting cancer and she isn't doing well at all so I totally understand why she might not come.