In laws trouble in paradise

My fiancé’s family had a party tonight and I’m 28 weeks pregnant with his baby and we have been together for 2 years everyone thinks we’re married and all but his family was getting ready to take family pictures and his cousins fiancé got invited to take it. His sisters boyfriend got invited and his mom looks at me and says can you take our picture? So I did but I am legit now crying in tears. Sick of this crap. I feel like tomorrow I’m just gonna be a straight up bitch to them.