I agree with you, except I don't think she was doing fine before the last kid. She ran her car into a tree in season three because she was exhausted (and perhaps drunk from day drinking with Ashley). She was already at her breaking point before she had Chase, but her husband didn't seem to give a shit then and he still doesn't. As frustrating as I found Monique in this episode, I feel really bad for her.
I also remember her saying that Chris picks fights with her around her birthday in season three, because the focus isn't on him. Still true, it seems, in season five. If she did have that