My dad's ex was at our house with her kid's visiting.
Dreams about specific people, such as your dad's ex, can often be symbolic and represent qualities or characteristics of the individual rather than the person themselves. With that being said, seeing your dad's ex in your dream could represent some unresolved issues or feelings related to your relationship with your father.
Alternatively, this dream could indicate a need for closure or resolution with regards to past relationships or situations in your life. It could also suggest that you are trying to come to terms with something from your past that is currently affecting you in the present.
The fact that her children were with her in the dream could indicate that you are feeling a sense of responsibility towards others and the need to be supportive and nurturing. It is possible that you have recently taken on a caretaking role in your waking life or are feeling a desire to do so.