11/19 -- Diddy continued his tribute to Kim with a slideshow of the 2 of them and their kids, writing, "I'll raise our family just like you taught me to. Love you forever!!!"

2:12 PM PT -- Kim's son, Quincy, just posted a message about his late mother, saying ... "I am broken...& the only thing that makes sense right now is that you were way too good for this silly world we live in. I love you so much MOMMY. Please give Mee-Maw the biggest hug and kiss for me."

Quincy is Kim's son from her relationship with Al B. Sure. Diddy took him in as his own at a young age. He's the first child of Kim's to address her death.

Diddy just addressed the tragic death of Kim Porter for the first time with a touching video and message about the mother of his children ... this almost immediately after he took an incredibly solemn-looking walk in public.

The Bad Boy honcho posted the tribute Sunday on Instagram, which shows him and Kim doing a maternity photo shoot with Essence magazine in December 2006 ... as he cradles a then-pregnant Kim, and they share kisses between shots.

He captioned the video with a somber message that read ... "For the last three days I’ve been trying to wake up out of this nightmare. But I haven’t. I don’t know what I’m going to do without you baby."

Diddy continued ... "I miss you so much. Today I’m going to pay tribute to you, I’m going to try and find the words to explain our unexplainable relationship. We were more than best friends, we were more than soulmates. WE WERE SOME OTHER SHIT!! And I miss you so much. Super Black Love."

His tribute came after paps caught him taking a stroll through Westwood Village, where he was wearing his heartbreak on his face. Sad is an understatement ... Diddy looks absolutely devastated here.

We broke the story ... Kim was found dead at her home Thursday from complications stemming from either pneumonia or the flu. She birthed 3 of Diddy's children -- D'Lila, Jessie James and Christian. She was pregnant with D'Lila and Jessie during this shoot.