Just found out that someone who was recently hired to the same position as me at my workplace is getting $3/hr more

After nearly 5 years here, I've gone from $15 to $18, and they've hired them at $21… I'm so exhausted and depressed, I wish I could quit. I'd organize my workplace if I knew how, or were good with people. The bosses praise me constantly and acknowledge the quality of my work, and then stab me in the back…