In the moments prior to Rhys" confession, Kirsty and her sisters are discussing the implications of the imminent change on their lives. Emotive language and tone together emphasise the drama and desperation of the sisters" concern. After being affirmed by her sister Dani that the family will "stick together no matter what", Kirsty implicitly replies "No we won't! If they get divorced, we won't ever be a family again!" The tone used is one of despair and the emphasis placed on the word "be" indicates Kirsty's recognition that the consequences of this change will be quite significant.
After Rhys" confession, Kirsty's supposed ability to deal with what has happened is destroyed and she decides to run away from home - a decision that, in her own mind, seemed quite viable. Escaping from the circumstances allowed her to calm down and try to realise the extent of the situation as well as providing time for her to reflect on how to react.
With regard to the use of language forms and features; as Kirsty is running along the footpath there is a blue tinge to the light, most likely from the moon. This is an example of low-key lighting and when viewed, the images appear quite stark and contrasting - a great symbol of Kirsty's emotions. Her mind is darkened and unclear by what has just happened and the light (or lack thereof) represents this. She can't see much, in terms of the situation and how to overcome it and the responder recognises this through the restrictions placed upon what is visible to them. In terms of "changing self", this feature enables the responder to see the virtually instant transition of Kirsty - from innocence and confidence, to feelings of bitterness and negativity as a result of an unexpected experience.
Gwen Harwood's poetry, in particular The Glass Jar, also explains this concept.
The process of "changing self" is clear in The Glass Jar with the idea of not accepting or acknowledging a significant change, especially when forced, being the most crucial - the young boy in the poem displays this.