Help 😤😤😤😤😤

My bf has two other kids with his ex gf there girls ones 6 & the other one 4 . I'm currently prgo 4 months I have no problem with his kids he see them because mother don't let come with us cus of me she don't like me. Anyways my bf been lock up so he was in oldest kids life for about 3 yrs and 1 in younges anyways he always talk about oldest my baby this & that it bugs he wants name our child just like the first one I'm like no u already have a child name like that idk if he's joking or serious anyways he told he loves oldest more bcus its his first child it just bugs I told him so u won't love mines& idk its bugs me so much.