Mil, said what?! Advice much appreciated!

This is going to be a bit long, so bear with me.....

So my husband and I eloped (2nd marriage for both of us), due to some complicated circumstances, but let all of our friends and family know that we would plan a huge celebration for them to attend at a later date. Everyone was super excited about this, including my mil. In fact, she was relieved that we were planning on an event she could attend.
We are now in the stages of planning and so excited to celebrate with everyone. We set a date, booked a venue, sent save the dates, etc. Up until this week everything has been great. Other than mil making a few comments here and there.... like "so what is it? An Anniversary party? A vow renewal?" We kindly correct her and let her know that it's a celebration of our marriage and basically a big party so everyone can get together and have fun.
Fast forward to a few days ago. Our neighbor invited my in-laws and us to their house for dinner. We were having a great time. Our neighbor then mentioned that they recieved our save the date and wanted to know a little more about the event, as they knew we were already married. (This information is in the save the date, as well as the website, but we still get questions here and there, from those that don't know us as well).
Before my husband or I could answer, my mil jumps in and says "they're having a vow renewal", in a sarcastic way, that gave the impression that it was ridiculous. My husband then says "no mom, were not having a vow renewal or ceremony, it's just a big party so we can all celebrate".
Then comes her comment, from out of nowhere, in a non-non-joking demeanor, "you already had your wedding". Now it's not what you think. She isn't talking about our marriage. She then goes on to talk about my husband's ex-wife, whom she hates btw, and how he already had his wedding.....
My husband immediately jumped in and said something witty, like are you seriously talking about my marriage to her?! The subject was quickly changed after that.
We have been together 7 years, 7! It's not like he just got divorced from her.
Anyways, after the dinner, I voiced that my feelings were hurt to my husband and fil, to see if they took it the same way or if I was just interpreting wrong. They both agreed. My husband didn't understand what her problem was, as she was always excited when they had talked about how the plans were coming along. Fil agreed that she didn't say it in a joking way and said it was kind of an a****** thing to say.
Needless to say my feelings are hurt. I understand that we eloped and there could be some underlying emotions there... but it didn't seem to be that. Anyways, I can't stop thinking about the comment. It's left me sad, angry and disappointed that she doesn't see our union as worthy of a celebration because he "already had his wedding".