Why do i feel im not part of the family ?

i just feel so left out, Its my birthday today but they dont even bother inviting me to the outing. Even if they do and i accept they just say “Just stay here, its not that far anyway” im upset. so upset. they just came back and they just locked the door. They laugh so hard i want to cry. Ive tried playing with my brother but he always justs declines and calls the game i want to play with him “ive seen it, its horrible” , “That games trash” then proceeds to play with my step-dad woth the game he just called “trash”. My step-dad wont even talk to me. Yeah, im not that social and an extrovert like my brother but can you atleast try to talk to me? I feel like the only people i actually consider family are my friends that ive had since kindergarten.