From your post, your BF is a trash. How could any decent person treat the mother of his child like this? ("他就消失了,期間隻給我發了2封郵件,第一封建議我去流產,當時孩子已經將近22周,第二封告訴我我不是個好人,時間會證明一切。")
I think adoption is a valid choice for you. You can select adopting parents, i.e., find a good family for the baby. I do understand that no mother wants to give her own baby away. However, the reason should never be that "wish the baby's father to come back to me one day". Being a single mother is tough; but very doable, especially in the States.
No matter what your choice is, good luck!