So upset and just need to rant.

Today was my baby shower - it was supposed to be fun and great but I let stupid family drama ruin my day. 
I sent the hostess the invite list over a month ago and forgot about it. Since then, I have quit my job because I was concerned about my safety at work, been bedridden by bronchitis, helped my husband start a new job, tried to juggle graduate school, stressed about insurance and have generally just had a rough go of things. Needless to say, I haven't had much time to think about my shower. In fact I forgot about it being this weekend until my mom reminded me last night. 
Well come to find out, invitations weren't out by the hostess and I never knew a thing about it. My mom sent Facebook messages to people she knew would be able to come to make sure that people were there. The only way I found out invites weren't sent in a timely manner was when my neighbor told me at 8:30 last night that she couldn't come due to other plans. Things happen, I wasn't mad. It was all fine. I try not to let things bother me and I let the invitation thing go. 
This morning (and by morning, I mean noon lol) my husband woke up to a string of texts from his sister saying how upset she was that she didn't get invited to the shower (she saw someone post about it on Facebook). She attacked both of us and called us rude, inconsiderate, and just plain terrible people. She said that he needs to step up and say something when his wife is neglecting his family. He called his dad to explain exactly what happened - his dad called him a liar and hung up on him. I'm walking into my shower when my husband calls to fill me in on the drama. 
1) We did not intentionally exclude them from coming to the shower. They live 12 hours away and would not be able to come. But I made sure they were on the list anyway. In fact, I've made an active effort to include them in this entire pregnancy whenever possible (gender updates, ultrasound pics, etc.)
2) Maybe I should've called them to let them know about the shower. But I feel like I did my due diligence by handing over the invite list. And I've been so unbelievably stressed that it has been the farthest thing from my mind. Am I wrong?
3) They blew this WAY out of proportion and when presented with the facts, they called us liars. How do you rationalize with someone who doesn't believe the truth?
I have been crying about this all day and literally don't know what to do or say. This is the part I hate about having a baby. Somehow, someway people get hurt. And now I don't feel like I can post the pics from today because I know they're going to say something about it. I just feel so defeated.