Preheat oven to 425°F. In a medium bowl, whisk together barbecue sauce, apple cider vinegar, and water. Set aside.
Pat chicken breasts dry and lightly salt and pepper both sides. Heat a large skillet with a lid over medium-high heat and melt butter.
Add chicken breasts to the pan and cook until lightly browned. Flip the chicken breasts and pour barbecue sauce mixture over the top.
Bring sauce to a simmer and reduce heat to medium-low, keeping the sauce at just a simmer. Cover and cook for 5 minutes. Flip the chicken, re-cover, and continue to cook until an instant-read thermometer inserted into the thickest part of the meat reads 165°F, usually around 3 to 6 minutes more.
Transfer the chicken to a cutting board, and allow it to rest for 5 to 10 minutes. Allow the sauce to continue simmering uncovered, stirring occasionally, until it thickens.
Shred chicken breasts and return shredded chicken to the pan of sauce. Stir until well-coated.