No idea where this came from

UPDATEI posted the original about a month ago where my ex started crying after she learned I was talking to a woman. Fast forward about a month from that post and my ex sends me a text in the middle of the day that only says "everything is wrong". That's it. She's a teacher and got a new principal this year, so I thought she was talking about that. But no. When I asked her what was going on, she did mention her job, but she also said "us". She than sent another text saying that everything was wrong the way it is, but she didn't think that there was anything she could do about it. I responded by saying that this wasn't a conversation to have by text and left it at that. This morning she texted me asking me if that was a conversation I would want to have. I just don't understand what's going on in her head. She's been living with a guy for 9 months that moved halfway across the country to be with her. She hasn't come right out and said the words, but it looks she's thinking about reconciling. It's been 4 years since things started going seriously downhill. We lived as roommates for 2 years, and we've been physically separated for another 2 years. The obvious change is that I started talking to another woman. Because of my kids, especially my daughter, I have to maintain a relationship with my ex. But I'm very conflicted about this. I can't just pretend the last 4 years didn't happen. My natural curiosity wants to figure out how her mind is working, regardless of our past history. But I know that this situation is ripe for manipulation.