"Depression is a really awful demon to battle, and during lockdown it's scary," she said.
Cassidy said her hiatus on social media for the past few days has been due to her "fragile mental state".
"I'm feeling very empty and defeated at the moment with our current situation. I have never missed my family like I have this past week.
"I would do anything to squeeze my mumma right now. I can't wait to squeeze my siblings. My chest hurts with how much I miss them."
Cassidy said she is "beyond thankful" for her friends and family for their support over the past week.
"I send my love to anyone who needs it right now. Take this as your sign to keep pushing. The light at the end of the tunnel is coming," she said.
Cassidy also revealed she recently received her first AstraZeneca COVID-19 vaccination, and encouraged others to get jabbed.
"I didn’t get the jab for me. I got it for my mum. For my brother and sister. For my friends, frontline workers and for the small businesses. I got it for the community," she said.
"Was I nervous? Absolutely. Am I scared for the potential risks? Sure. But do I trust my medical professionals who guided me through this choice? 100%. And I urge you to do the same."
The influencer urged her followers to speak with their doctors or healthcare professionals before refusing to get vaccinated.
"Ask the questions you have. Speak about your concerns. Believe me I had so many. But my mind was put at ease by my doctor who I trust," she said.
"Remember - to willingly choose to not get vaccinated when it’s available to you screams privilege, and I would like to remind you of how many people from around the world, would do anything to be in your position."
Cassidy warned her followers that she wouldn't be tolerating "any propaganda" from anti-vaxxers or trolls on her page.
"You will be blocked immediately. So if it's not a comment open to peaceful discussion, please refrain," she said.