Sounds to me like your aunt is just using your cousins situation as an excuse. Likely, she has other reasons for not going, but doesn't want to disappoint you by making you feel like she can't make it a priority. So she has found an 'out' that doesn't place the responsibility directly on herself.
People are often motivated by their emotions or lack thereof. And act in strange ways that can easily be misinterpreted or only seen for face value by those who fall victim to their actions. Recognize that you have no control over how others act/feel, but you do have control over how you accept/react to their actions/feelings. Sometimes you just have to step aside and choose not to be a part of someone's drama. I think this advice can be applied to your aunt as well as to the member who tore a strip off you earlier in the thread.
As a human being you are entitled to feel. Your feelings are always valid, regardless of rationality. I think what you were looking for here was an outside perspective, not a chastizing.
Focus on yourself, within this process, and not on how others are judging/dealing with it. You will have an amazing time, regardless. All that matters is that you and your groom get to the alter and say your vows. Everything else is just a story for the kids.
Good luck and HAPPY planning!