Complex sentence: Denise was icy and cutthroat, not just as CEO of Sandler Cosmetics, but in all other aspects of her life, but it didn't always get her what she wanted.
Split into simpler sentences: Denise was icy and cutthroat, not just as CEO of Sandler Cosmetics, but in all other aspects of her life. However, it didn't always get her what she wanted.