who is the victim in act 1?

This really depends on your point of view. All the characters are victims to a certain extent. Most of their anxieties, like Willy Loman, are self-inflicted. Still, I consider Linda Loman a victim of her circumstances. She attempts to put on a brave face while trying to keep her family together. She has aged well past her years because of her husband's delusions of grandeur and her relatively dysfunctional family.