Complex sentence: After graduating high school, she was accepted to the State University of New York at Geneseo but decided not to attend and took a gap year living with her aunt and uncle in Long Island, and working as a waitress.
Split into simpler sentences: After graduating high school, she was accepted to the State University of New York at Geneseo but decided not to attend. She took what is called a gap year off, living with her aunt and uncle in Long Island, and working as a waitress.