Undoubtedly, the person who suffers the most from Willy's delusions is his wife Linda. Although this may be an arguable observation, the evidence in the novel points at this being quite probable.
The character of Willy Loman in Arthur Miller's Death of a Salesman is a sixty year old man who has achieved very little in life because he has embarked in a never-ending quest to hit his version of the American Dream: One which can be obtained quickly and painlessly if only one is well-liked and good looking.
Living under that philosophy, Willy has brought more grief than joy into his household: He has raised two sons under his "spell", turning them into immature womanizers. He also has cheated on his wife in the quest of being "well-liked" and "popular", and he has brought little earnings to their finances. After all, Willy has done nothing but to live off his "dreams" of making it big, which are wrong from the beginning.
With time, Willy's illusions have turned into delusions. Literally. Now in his twilight years, Willy has come to the realization that his life has really amounted to nothing. His way of solving his "unfinished businesses" is by reverting back to time in his tired and foolish imagination, where he has the chance to make amends with his past. All these dynamics, from the beginning until now, are witnessed by Linda on a daily basis. Linda, who always remains in the back of the plot, stays quiet, and perhaps even suffers in silence.
Already in Act I we can perceive the pressure that Linda endures living with a man as unreliable as Willy. In this Act, Willy comes to Linda with the news that he has crashed his car again. This is one of several instances that Linda knows of in which Willy has crashed his car. He has tried it before, and he has also tried other forms of what is later known to be suicidal attempts.
Not alone with that, Linda is the bearer of the choices that Willy makes: During her entire marriage she has spent most of the time in her home alone as Willy travels around in foolish sales trips that always come to nothing. Poor Linda Loman plays no role in her family, but she gets to tolerate every bit of her family's dysfunctional nature.
However, Linda does not seem to complaint. If anything, she defends Willy and even goes as far as challenging her own sons to be better to him. According to Linda, Willy is just "lost" and needs to be grounded. She also feels that he needs compassion and understanding.
Yet, when Willy finally succeeds in completing his suicide, Linda still does not understand what is wrong in the first place. She understands the nature of Willy's pain and the fact that he really has a dream that he had wanted to get. Yet, here is Linda being left alone by Willy one more time after his suicide. She simply never gets much back.
Therefore, Linda is Willy's only support system, but she is also the one person who gives him her all without asking for much back. For this reason, she is the silent sufferer who witnesses how her husband breaks down for good.
The most obvious answer is that all suffer and this would be a true answer. However, if you have to narrow it down, there will be lots of opinions. In my opinion, the one who suffers the most is Willy's wife, Linda.
As the work progresses, it is clear that Linda is a loving and supportive wife. However, as we see Willy's grand dreams and alter reality, our heart goes out to Linda, who has to live with this her whole life.
Also when we read between the lines, she is the one who holds the family together in the midst of Willy's misguided dreams and desire. In other words, she needs to pick up the pieces and make sure the family is well. She also has to be Willy's supporter through all this. What else could she do? Finally, when Willy commits suicide, she will be the one who will have to live on with her boys and deal with the loss of Willy.
In this sense, Willy's death is a tragic release, which Linda does not have the liberty to have.