Wow, this was wonderful! I loved your poor grieving Harry and the Severus-induced improvement in him. The death of a spouse is something that can take a lifetime to heal. I also loved Harry's kids were in this, especially your "Lilyflower." Loved your epilogue too - the last line was great!
I swear I don't read stories intending to look for this stuff, but: - I think the word in "diffuse a situation" should be "defuse" - In the second paragraph of the epilogue "brining" is probably "bringing"