It was an incredibly big message.I do not think they text such messages to people they do not care about. I am sure that they were together at that moment.(my ex almost every day at that hour was at home with her best friend).When we broke up with my ex, I texted her best friend. It was the only time we communicated. As it turned out, she showed my messages to my ex, after that I had no desire to text her again. I think they thought that I would ask her best friend about my ex. I think they did it to just raise her self-esteem ( once again, they wanted to know that I still have feelings to her) In fact, you are absolutely right. Why once again I think about her? If she wanted to return, she would try at least to continue the conversation after the congratulations. This did not happen, so everything is clear here. Most likely you are right, and she just congratulated me. Sometimes a banana is just a banana and I need to stop myself from overthinking.
Thank you for your reply!