[X] Explain Sayaka to Homura, using
this post as a knowledge base.
-[X] Her personal character: who she is, what her central characteristics are, etc.
-[X] Her actions: why she has done what she has done in the past.
-[X] Her present actions: why she's doing what she is doing now.
-[X] Answer, as possible, any questions Homura may have, as they develop -- this is a talk, not a speech. If there's something the knowledge base isn't equipped for, break.
-[X] Slip in compliments towards Sayaka wherever possible. These topics are going to be pretty negative, but... Sayaka's a good person and friend, who would absolutely have jumped at the chance to help Homura if she'd only ever really known the way you do.
-[X] Explain that this is why you're so positive about telling Sayaka about the loops, but reiterate that you're never going to press Homura over it.