You gave too much rein to your imagination. Imagination is a good servant, and a bad master. The simplest explanation is always the most likely.
In family conflict, parties often have wild imaginations. The breach of trust which leads to the end of the relationship throws all certainties into doubt. Even if there has been a long history, the parties can feel as if they no longer recognise each other. This is also typically when communication breaks down. Into this vacuum, imagination pours fears, interpretations and dire prophecies.
Some of these beliefs are related to the changes in behaviour/actions/choices of each party as the relationship disintegrates. However, many of them spring from allowing our imaginations to run wild. As Agatha Christie, notes imaginations are a bad master. If there is a concern, much better to raise constructively. Through mediation, we can work to create a new paradigm for communication and a world without assumptions.