AITAH if I call off my engagement because of a comment my fiancé made about my late wife?

For some background info I (43m) have 2 children with my late wife Kayla. Sam (21m) and Liz (16f). All fake names. Kayla passed away when our kids were 15 and 10. I won’t give specifics about how she passed but she was struck by a drunk driver when she was on her way home from work. She really was the love of my life and to say that her passing hit our family hard would be an understatement. I promised myself that if I got back into the dating game I wouldn’t date anyone for at least a couple years for the sake of my kids. 3 years after my wife’s passing, I met my now fiancé. We’ll call her Amanda. Things went slow and I didn’t introduce her to my kids until we had been dating for about a year at that point. Now we’ve been together for 3 years and are engaged. Amanda and my kids have always had a good relationship. Neither of my kids are super close to her but they have always been friendly and welcoming to her, and Amanda has never overstepped any boundaries my kids have, like trying to replace their mother.

At the beginning of Amanda and I’s relationship, she was a bit insecure of the fact that I was a widower. During the first few months of us dating she would constantly ask things like “if Kayla had never passed, would I still be with her right now.” I always kept my answers brief, and told her that I didn’t like thinking about the “what ifs” and that she was the one I was dating now and that was what mattered. Eventually she stopped making these comments and I stopped worrying about it.

Now to the issue. My parents were hosting a family dinner to celebrate my fiance and I’s engagement. It was my mom and dad, my late wife’s sister and her husband, Sam and Liz, and me and Amanda. Dinner was going well, we were all making small talk with each other and talked about wedding plans. About half way into dinner my mom made a comment about how she was “so happy I was able to find the spark I had with Kayla in someone else.” I don’t think anybody really paid much attention to the comment but then Amanda laughed and said “I’m happy she died, otherwise I would have never gotten him to myself.” The tone of the dinner immediately shifted and everyone got extremely tense, especially my kids. Amanda noticed the shift and started awkwardly laughing like she was trying to play her comment off as a joke. I was honestly just frozen as that was the first time she had made a comment like that. My kids looked disgusted and Liz got up and walked out to the car. Sam waited a bit longer like he wanted me to say something but I was still in shock about what Amanda had said.

To make a long story about the dinner short, the dinner was kind of ruined, so I said my goodbyes to everyone, grabbed my fiancé and we all drove home. My daughter hasn’t spoken to me or Amanda since and it’s been 3 days. I got tired of it and pulled my son aside to ask him what I should do. He said something along the lines of “I’m a grown man and don’t care who another grown man marries, but I don’t want a women who speaks like that about our mother around my sister.” Sam’s comment stuck with me and now I’m considering calling off the engagement entirely. She’s never made comments like this before but I’m worried if I let it slide this one time, it will become more frequent and it will affect my daughter. I need some advice from outside perspectives and just want to do right by my kids. WIBTAH if I called of the engagement because of the comment she made?

Edit: Wow I didn’t expect to get this much advice so shortly after posting this. Nonetheless thank all of you for the advice and even the people calling me a bad father. I think your guys words are what I needed to pull my head out my ass. I will try to talk to my kids alone tonight before speaking with my fiancé and we’ll see where it goes from here. I’m pretty sure my fiancé and I are over though. I’ll update late tonight or tomorrow on how the talks with everyone goes. Thank all of you again for setting my head straight.

EDIT#2: I tried posting my update on here but this post wouldn’t allow it. I’ve made a separate post for the update for those interested.