2 and 3 on your action list are good plans but will you respond if he initiates between now and 6 Jan? or are you only talking about initiating contact
with regard to 1.
I would be tempted to stick with just 'XXXXXXX is the book i mentioned the other day, i found it really interesting.
you could add a 'let me know what you think'
if you want to throw in the validation, which i'm not sure is a great idea, then you might want to consider something like
'Thanks for sharing your feelings. I know that it can be difficult so i'm pleased you felt you could'
the added bit is a reminder that he felt safe with you at that time and i think adds sincerity to the thanks because it shows you felt it was a positive thing
Both mid 30s, 2 young kids BD 7sep14 XW moved on long ago, now living with OM1 D paperwork in progress