The 46-year-old singer - who is currently in lockdown in Los Angeles with his wife, actress Ayda Field - has revealed he's been fighting "fear and panic" over his dad's health amid the coronavirus pandemic.
Robbie - whose mother-in-law has Parkinson's and lupus - shared: "We've got a lot of family issues right now.
"My dad has got Parkinson's, my mother-in-law who I love dearly has got a very big illness. We can't get to them. My dad is thousands of miles away.
"My mum is just a year short of 80 and she's in isolation and I can see the things whirling in her mind and her eyes going."
Robbie initially worried that being in lockdown - and the sense of helplessness it's created - could have sent him spiralling towards depression.
But the chart-topping star has managed to successfully navigate his own "fear and panic".
He told the Daily Mirror newspaper: "I noticed at the start of the lockdown that I was going into fear.
"But the difference between me now and the person I used to be ... I saw it, thought 'That's interesting - tomorrow will be different'. And it was.
"Whereas before I used to think that I'd feel that way for a decade."
Meanwhile, Robbie previously confessed that at one stage in his life, he was "unable to leave the sofa" for three years as he battled agoraphobia.
The 'Angels' hitmaker admitted the anxiety disorder - which causes people to avoid places or situations that may trigger panics - left him housebound for years.
He shared: "My career had gone stratospheric and taken me to Mars, and I needed some time to get my equilibrium back and get myself back together. It was my body and mind telling me I shouldn't go anywhere, that I couldn't do anything. It was telling me to just wait - so I literally just sat and waited.
"I was agoraphobic from around 2006 to 2009. Those years were just spent wearing a cashmere kaftan, eating Kettle Chips, growing a beard and staying in."