In The Spaniard's Bed by Helen Bianchin

Diego de Santo: dynamic, charismatic, he’s made millions — and he believes everything is for sale. Cassandra Preston-Villiers: heiress to an empire, she’s beautiful and sophisticated — everything Diego’s ever wanted in a woman — so he blackmails her into becoming his mistress.But now that he’s got Cassandra, Diego wants more — an affair is no longer enough for this hot Latin lover!