There is a bit of Hemingway in this character (a writer visiting Africa), but that biographical information is not necessary to understand the character. Harry's leg has become infected and he realizes he is dying. He is nonchalant about it, perhaps in denial. He is flippant with how he deals with Helen. When she asks if there is anything she can do for him, he says she could shoot him, remarking that she's a good shot. Helen truly cares for Harry, but he does not feel the same.
In his frustration, Harry tells Helen that he never really loved her. While this may be true, he is acting out of selfishness in his dying moments. There is the indication that Harry has stayed with Helen, not out of love, but to have a companion who happens to be rich.
In his bitterness, Harry debates with himself as to whether she or he killed his talent. One of his continuing regrets throughout this process is that he will no longer be able to write:
She shot very well this good, this rich bitch, this kindly caretaker and destroyer of his talent. Nonsense. He had destroyed his talent himself. Why should he blame this woman because she kept him well? He had destroyed his talent by not using it, by betrayals of himself and what he believed in, by drinking so much that he blunted the edge of his perceptions . . .
Harry has flashbacks to more poignant moments in his life, such as his experience in the war: moments worth writing about. Harry feels as though he's sold out, being with rich women, Helen being the richest, rather than being with someone he loves. In short, Harry is bitter about dying and what his life might have been. He unfairly takes it out on Helen.