The TOWIE star, 30, described how she had a "huge hole in her heart" after the death of her beloved grandmother in December.
In a heartbreaking message posted on her official Twitter and Instagram accounts, Jessica wrote: "Didn't think this day was ever going to come & it doesn't feel real. I have a huge hole in my heart.
"It goes without saying that heaven just gained a beautiful angel with the biggest heart I've ever known. The most selfless person I've ever known. Your big heart, kind eyes, sensitive nature & hilariously charismatic self is what we all, including the nation, fell in love with & its what I'm finding so hard to live without."
In a long message shared with her 2.6milion combined followers, the singer continued: "I'm taking peace in that you're with the love of your life, our grandad again. The bond a grandchild has with their grandparent is unexplainable & the love we have is so special.
"The times we spent alone one on one will remain in my heart forever I miss them too much, our chats, your advice & just your general sweet being. Us grandchildren love you with every inch of our hearts & we will watch your amazing qualities in all of our parents, your children."
Jess goes on to describe her Nan as "my favourite person ever" and thanking her for "showing me how in life we should all be as kind as you" and "how to laugh everyday no matter how I feel".
Jess' fans flooded her with messages of love and support, with many also mourning the loss of the TOWIE veteran.
One wrote: "Stay strong beautiful and send my love to you and your family and she will be so proud of you love you Jess."
Another said: "I can only imagine the pain u are going through, may the love of family & friends comfort you through this difficult time x."
A fan said: "Nanny Pat would be so proud she would be smiling down on how proud she is of u this brought a tear to my eye x."
One more described the late reality TV star as "a national treasure".
On Friday (8 December), Nanny Pat was laid to rest in Essex.
Friends and family of the beloved grandmother - real name Pat Brooker - gathered to pay their respects to the 80-year-old, who passed away just before Christmas following a short illness.
The coffin was taken to the funeral service in a white carriage pulled by horses with purple plumes attached to their reigns.
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