Help, what do I do

My fiancé an have been together for nearly 2 years now, and i feel like im being pushed aside, im 34 weeks and 1 day pregnant today with his baby, he is constantly on the phone or messaging a girl called jess who is also pregnant aparrently but its not my fiancé baby, but he spends more time on her then me an his unborn daughter, it feels like they are in a relationship behind my back, he see's her near enough every Saturday, whilst im at home heavily pregnant as i only have 6 weeks until my lil girls due date. what do i do how do I get him attracted to me again and wants me an not them 😢😢