Complex sentence: After beating and tying Sheelagh up, David made his way to the hospital to try to kill the real Gabriel by suffocating him with a pillow as he thought his brother was dead he left luckily doctors saved him without David's knowing.
Split into simpler sentences: After beating and tying Sheelagh up, David made his way to the hospital to try to kill the real Gabriel by suffocating him with a pillow. As he thought his brother was dead he left; luckily doctors saved him without David's knowing.