The light is on the high end of good. Cattleya hybrids, and most species, bloom better with more light.
The leaf split because the roots couldn't supply the water required for your conditions of light, temperature and relative humidity. This could be because you didn't water enough, or your relative humidity is so much lower than it was at the grower's facility. It is unlikely you rotted the roots with overwatering.
Read the thread about
using a skewer to decide when to water. Water most Cattleyas a little after they are dry. When in sheath, water just before going dry.