Really,I know this. Why the hostility? The obvious bs excuse she felt she needed to give me upset me. Just be honest and I wouldn't have a problem. I really would have been fine if she had said she couldn't make it. I wasn't expecting everyone to say yes. This Sister in law by the way is extremely selfish and into herself. She was invited to my dd's HS graduation (she is dd's god mother) and didn't come (which is ok not a problem, it was her birthday) but she calls my DH during the ceremony because he didn't call her to wish her a Happy Birthday and was angry because he wouldn't talk to her, She consistently doesn't show up to important family events, but expects everyone else to come to hers.
My DH's Mom passed away 6 yrs ago. She was hospitalized 2 yrs before she passed and DH and I were at the hospital twice a week to help her and visit, all the sisters were and DH and I alternated so someone was always there with her.
For the poster who asked why I added the born again Christian comment, it was just because she accused me of stealing her " joy" .
So, really, you are here for validation, not outside perspective, right? Because almost everyone is giving their outside perspective and pointing out that your actions were rude, but you just keep coming up with more reasons why you are the victim and your SIL is an evil witch.
Still not seeing the connection between "stealing joy" and your comment about her being a born-again Christian, but oh well.