Going CRAZY !!

I just need opinions to clear my mind and maybe get my thought clear! So I have currently been super stressed because I want to be with the love of my life but I feel like I can’t because my mom has an 8 month old and I’m about to be 21 but I don’t want to leave her since no one can take care of my sister for us.. we have been having problems with 2 family members and they turn my grandfather against her and he screamed at her today and all I want is to go with the man i love and save money to buy a mobile home so she can be stainless is it selfish of me wanting to go and do that ? Should I stay here at help her ? Someone please give me advice I’m losing my head 😪