Complex sentence: "Bleeding Love" became the best-selling single of 2007 in the United Kingdom, and, since the single's release, it has become a major international hit as the world's best-selling single of 2008.
Split into simpler sentences: Bleeding Love became the best-selling single of 2007 in the United Kingdom. Since the single's release, it became a major international hit, and was the world's best-selling single of 2008.