Kelly Osbourne‘s letting folks in on her grieving process in the wake of her father Ozzy‘s death … which she says is the toughest thing she’s ever been through.

Ozzy’s daughter took to Instagram Monday and got emotional as she shed some light on what it’s like for her to lose her famous father.

Kelly says … “I’ve sat down to write this a hundred times and still don’t know if the words will ever feel like enough… but from the bottom of my heart, thank you.”

Kelly adds … “Grief is a strange thing-it sneaks up on you in waves. I will not be OK for a while — but knowing my family are not alone in our pain makes a difference. I’m holding on tight to the love, the light, and the legacy left behind.”

She ended by thanking fans, followers, friends and family for being there for her … and sent them love.