Can they give me child support if he isnt corroborating?

So my baby daddy left us . Basically wants nothing to do with us anymore. Wants freedom and friends and women. My 2 year old and 1 year old is traumatized. I dont even make much from my job but i do have an apartment a roof over our heads and basically pay everything for the kids. I had to beg him to give me money for pampers… so if he’s gone now what do i do?💔 do i get fulll custody now that they are with me and hes gone? And child support) ? Does he have to sign papers for me to get child support or the government just does it for me without his consent because i know he wont give me nothing!! I know he wont go to court nor sign or nothing give me nothing Outta his paycheck thats the way he is :. He makes more than me.. how do i do this😭