"I'm definitely his stepmum, we're full time now and I look after him a lot," she told the publication.
Jessika debuted her relationship with James in early March when the couple were enjoying a romantic break on the Gold Coast.
Last month, the reality TV star shocked fans when she shared an ultrasound image to her Instagram.
"💛👶🏼 here is a photo of my little angel heart gifted straight from heaven," she wrote alongside the sweet photo.
"My little sidekick and someone who already has my heart hook line and sinker 🎣"
However, it soon came to light that the bun in the oven doesn't belong to Jess, but it is actually her younger sister, Eliza, who is pregnant.
"IM GOING TO BE AN AUNTY 🤱🏼 and I’m going to love and cherish my niece or nephew so so much (and possible spoil him/her rotten) but more importantly I’ll love him/her more than I love myself (and that’s a damn lot🤦🏼♀️) 🌷
"I can never thank my beautiful baby sister and her caring partner more for gifting me with the title as aunty!" she shared.
And the 28-year-old is clearly excited for the new arrival, adding: "It’s something so perfect and out if this world 👼🏻See you soon my little angel, aunty Jess loves you so so much already #2020baby"
Fans were quick to congratulate Jess, with some admitting they at first thought she was announcing her own pregnancy.
One follower wrote: "I thought you were saying you were pregnant and oml I gasped so loud ahahah ❤️❤️"
"I was about to say congrats to you lol," said another.
Last week, Jess weighed in on the current MAFS season and claimed intruder Drew Brauer was “offered a wife swap” storyline by the show’s producers.
Speaking to Hit FM Mid North Coast's Krysti and Bodge on Wednesday, Jessika claimed that Drew told her the show’s producers had suggested the storyline, which he refused.
The blonde told the radio hosts the alleged incident took place following a two-week hiatus from filming, which apparently occurred as a result of the drama on the show.