The best interpretation supported by the poet’s description of his aunt is: The poet feels that the public perception of the war is inaccurate and that the reality is much different.
This interpretation aligns with the poem's themes, as it highlights the disconnection between what people might say about the war and what it truly entails. The phrase "my sweet old etcetera" suggests a simplification or glossing over of complex realities, indicating that the poet is critiquing superficial understandings of the war rather than endorsing it or presenting a straightforward narrative of family support or necessity.