Anyone else's family secretly hanged out with their ex?

Before I went NC, there were multiple occasions in which they invited my ex for a meet up/birthday party which they knew I couldn't attend, and did so behind my back. I had to hear from my ex that she had received an invite and that she didn't know whether they had told me about that. My family knew that we had broken up, and the last invite was even after I had told them that my ex had an addiction and was manipulative. Why would they do something like this? It doesn't make sense.

Did anyone else went through something similar?

Ever since going NC, I'm in therapy and just recently realized that what they did was extremely disrespectful to me.