The singer shared last month that she’d had a miscarriage after deciding to have a baby on her own and said her sadness was “overwhelming”.
She has now opened up in a moving Instagram post, saying she has been changed “forever”.
Jessie, 33, told fans: “I posted about losing my baby just hours after I was told. I reacted in work mode. It’s safe to say I sometimes pour more energy into creating a unhealthy process of my own pain in front of a camera, than I do acknowledging it behind one in real time. 'The show must go on' mentality reacted before the human in me did.
"I must justify to the audience for my show tomorrow, and explain to the world why I might be a little off, was my first thought. I must turn this into a inspirational, I know I will be ok, strong moment, because that’s who I am right?
"Truth is, I just needed to f****** cry and fall into someone’s arms and sob. But at the time I was alone. I hadn’t processed anything. Nor did I have any idea what I was about to go through not just emotionally but physically after this show."
The singer, whose real name is Jessica Cornish, said she now really understands “why women so often talk about the want and need for miscarriage to be openly spoken about more”.
She went on: “As I have learnt now that what people know of miscarriage to be (including myself before this past 2 weeks) unless you have personally experienced it. What people think it is, is in fact not a true reflection of what it really is at all. How can people support when they don’t know?
"I have never experienced pain and trauma or felt loneliness like it. This has changed me forever. In the most, heart-breaking, but beautiful way. It’s put life into perspective in a way nothing else ever has.”
The singer said she was so sorry for anyone going through it, saying that “losing your baby is one of the worst feelings in the world”.
“I ache for you,” she said. “If I could I would bring you food, hold you through the physical pain, I know that’s needed more than a 'stay strong' text right now."
Watch: Jessie J reveals she recently suffered a miscarriage
“I guess I’m here to say to anyone who may not have been told this, you are allowed to be broken.
"You are allowed to cry. Allowed to be weak. Allowed to be exhausted from the pain and the bleeding and the grief that barely has space to exist. You are allowed to do this however YOU need to."
"Sometimes life just calls us to be human," she added.
"We know there will be sunshine, but we can’t avoid the rain."