Complex sentence: What happened when St.Laurent was released from the hospital depends on whom you believe-according to Yves Saint Laurent, Dior promised to hold his job until his return, and that Dior intentionally deceived Saint Laurent to replace him with the more diplomatic Bohan.
Split into simpler sentences: What happened when Saint-Laurent was released from the hospital depends on whom you believe. According to Saint-Laurent, Dior promised to hold his job until his return, but intentionally deceived Saint-Laurent by replacing him with the more diplomatic Bohan.