my fiancé is about to leave me

ca
I'm not sure what to do. He's doing it because he doesn't want to hurt me anymore (we fight a lot)  and we are so different and I want to go to college but he wants to settle down right now. (I'm 20 and he's 23) guys he is my whole life and I lost a lot of my friends and family so if I loose him I will literally have nothing but my two dogs. I'm not sure how to handle this and I don't want to be self destructive or depressed if this happens. Does anyone have any tips??