I think you're fine for canon not mentioning Lily.  Dumbles didn't know Sev was still pining for her until he fired his doe patronus, and Sev would have been careful not to dwell on thoughts of her knowing that his mind would be invaded by his masters.Really, I think it worked better not muddying the waters with Lily (bad metaphor, I know) when you have such a compelling juxtaposition of Albus vs Tom going on in Sev's mind.

Very nice work, thank you for sharing.