Guys, I need to know my level of assholery on this. I feel terrible and want some advice on how to handle the situation because I love my grandmother dearly. 

A little background information, I grew up living close to my grandma and seeing her several times a month. Shes the grandparent I would consider myself closest to. Around a year ago I moved out of state for school and am now around 2000 miles away, so I only see her a few times a year. Even still, I feel like our relationship is strong. My grandma lives in a tiny town that no one in my family lives near anymore because everyones jobs took them elsewhere. Because of this, she says shes lonely. She is single and has two cats. She got her cats about a year ago after her old one passed away and these cats are her life. She says they have separation anxiety and she cant leave them alone or with anyone else for more than three hours. She said they will stop eating and may try hurting themselves if she is gone for too long. She stopped visiting my father/mother (3 hours drive away) around six months ago and says they have to come to her because she can't leave her cats. That being said, shes mentioned leaving for day trips with her brother and sister before and says her neighbor is a trusted cat sitter who the cats are comfortable with. She has no physical disabilities and is only 70. She retired two years ago and still drives herself/goes shopping weekly/goes out with friends and siblings every time I talk with her. 

My fiance and I just booked our wedding venue and are opting to have it in a location that is in between all of our guests. Everyone is spread out so everyone will have to travel a bit. When I told my grandma about this, she said she was sorry to hear I wasnt getting married within an hour or two of her and she would be unable to come. She said at first it was because she had no money. My father and I both told her we would happily pay for her transport , lodging, food, everything. It's that important to me she is there. Then, she said it was because of the cats. I asked if her brother or sister could take care of them for 1-3 days (they live ten minutes away) or if her cat sitting neighbor could help out. She said it wouldn't be possible because their lives would be put at risk. In my opinion, shes putting her cats over her granddaughter. It hurts badly and I cant understand why she is being like this.

I told my father I think she may have a mental illness and if he had any ideas for help, but he and the rest of my family laugh it off and just say shes "a crazy cat lady". 

It seems to me like she will not be attending, even though she is physically capable,financial capable with family assistance, has no other obligations, just is irrationally worried for her cats. I love my own cat dearly and can understand wanting it to be safe and comfortable while I'm away, especially if it has anxiety, but it seems like my grandmother may be projecting her own feelings of anxiety onto her pets.

Holidays are coming and I cant help feeling upset about my grandmother. I feel almost angry towards her for deciding not to attend. I feel like I cannot mention the wedding at holidays if she is near because she is upset with me for having it more than an hour and a half away.

Am I the asshole?