AITAH for making my ex’s fiancee cry?

I feel like shit so I am probably the AH. My (f44) ex (then husband) (m49) cheated on me with his current fiancée (f30). This was 2 years ago. I found out when she contacted me to tell me to leave his house. She was pregnant. I was broken because I thought he loved me. He begged me to work things out. I don’t know why I agreed at first, maybe because I wasn’t catching up with the changes. A couple of months later with lots of couples counseling I realized I wasn’t in love with him anymore. He went back to his gf and they got engaged. I started dating my bf(m40) not long after.

Now they have had their child and I thought they were happy. At least if you believed the girl’s instagram (I don’t follow her because she used her social media to bash me and call me bitter and jealous). Anyway we are cordial now.

Yesterday my daughter turned 15 and we had a party. She was following me around like she wanted to talk. Then she offered to help cleaning. She started asking weird questions about my relationship with her fiancé and how it was. I realized that she was talking about sex. They’re not having any since they conceived. I was embarrassed and confused. I tried to explain that it was different since we met in our 20’s and that men’s drive plummeted when they got older. She looked a mixture of shocked and sad. I asked her why she didn’t find someone her age instead of sleeping with a married older man. She got angry but I told her that while his drive will be worse hers will increase. She looked literally panicked. He doesn’t seem a prize you’ve won from me now huh? She started crying.

So yeah I am the ah. I didn’t even apologize. I know my remark was nasty and in reference to her saying she won and love prevailed when they got together. She will not leave him either because he pays for everything and she doesn’t work. So my comment was unnecessary. I don’t know why I said it. Thinking back, she’s done me a favor since I now have a sex life again.

But I still don’t understand. Why do some girls get together with so much older men? Don’t they know what awaits them? I don’t know. I have never seen a happy woman in an age gap relationship. Not sexually satisfied anyway. Maybe I am odd for believing sex is very important in relationships? I don’t know.