My divorced marriage found its way in to my new relationship

It seems like I’m in a bit of a situation so just kind of wondering how I should handle this. I, 29M, got divorced from my ex-wife, 27F, a little over a year ago. I had suspected her of cheating but could never find any concrete proof. All in all I didn’t lose much in the divorce other than my dog so I spent the last year and some change trying to move on. I started putting myself out there and trying to go on dates around March/April earlier this year. Nothing really worked out and I just started looking for straight hookups. I met someone, 30F, in May who had been through the same exact situation as me. Divorced, nothing had worked out seriously for her so just started looking for hookups. We immediately hit it off. We can understand each other, communicate openly, and the sex is amazing. We decided to exclusively start dating about a month ago. My now girlfriend had told me what she did for a living but not WHERE she was working (she works for a pretty big company that has multiple branches). Turns out, she is best work friends with my former mother-in-law! They eat lunch together, sit right next to each other, and work on different projects together. It also turns out that my former mother-in-law unknowingly told my now gf that her daughter (my ex-wife) just got divorced last year and was so happy that she could be with her boyfriend without having to hide it and how she was glad she wasn’t stuck in a marriage with me anymore! It’s worth noting that my current gf and I live in different towns about 30 minutes away from each other. And I moved away from my ex’s family. My current girlfriend lives about 45 minutes away from where she works. So it’s absolutely a one in a million chance that we’d all know the same people, especially this intimately. I was with my ex-wife for 10 years and was very close to her family. So when I heard that my ex MIL was saying she was happy that I was out of the picture, that definitely opened a wound I thought I had closed and made it a little worse. My gf doesn’t know how to handle this situation and I’m not sure I do either lol. If I keep dating my girlfriend, my ex MIL will eventually find out and definitely treat her differently at work and I definitely don’t want that, but I don’t want to stop seeing her either lol