Businessman and film producer Bing took his own life in June 2020.
Damian, 19, marked the first anniversary with an emotional post on Instagram.
Sharing a picture of a sunset, he wrote: “A year ago today, my mother and I received some devastating news.
“I didn’t realise at the time quite how much it would affect me... We all like to show ‘perfect’ versions of our lives - for me, the idea of publicly discussing something as personal as grief is terrifying... but sometimes it’s necessary.
“The last year has been b***** hard - for everyone on the planet - and I think acknowledging that is vital.”
“It’s not weak to struggle,” added the model.
“In fact, to get through to the other side is immensely strong.”
Damian also thanked fans for their messages of support, adding: “I love you all Xxx.”
Gossip Girl star Elizabeth dated Bing in 2001 and Damian was born in 2002.
Bing originally denied paternity, but a DNA test proved he was Damian’s father.
The spat led to the couple becoming estranged and it’s thought that Damian had little to do with Bing growing up.
However, last year Liz revealed that she and Bing had reconnected, saying she was “grateful” that they were back on talking terms before his death.
She told You magazine: “We hadn’t been friends for a very long time, but about a year and a half ago he came back into our lives.”
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