Three short lines, and almost all of the feeling sits in the last one. The speaker starts by calming someone down: "I'll be fine. I won't die." It sounds like what you say to a worried friend, or what you repeat to yourself when something has gone badly wrong. Then comes the admission: "I'll just hurt a lot."
That word "just" does a lot of work. It tries to shrink the pain, as if hurting is a small price next to dying. But "a lot" gives the game away. The speaker isn't really comforted, and the reassurance only holds up if you ignore the hurt.
The mood is quiet, tired, and honest. There's no drama or big imagery, only plain statements, which makes the pain feel more real. The speaker seems to be bracing for something, maybe a loss or a breakup, though the poem never says what. Judging by the tone, the point is that surviving something and being okay aren't the same thing.