Breakups can be hard, messy, full of recrimination. Take Davy Hickey, the hugely successful investment group behind the Citywest campus, now home to thousands of homes, shops and global businesses like Pfizer, BT, Unilever and Glanbia.  Over 30 years, the stalwart Davy Hickey Properties (DHP) built on a lucrative land bank in west Dublin and acquired a commercial portfolio from Paris to Leeson Street in Dublin worth hundreds of millions of euros.  When property tycoons like Sean Dunne and the late Liam Carroll were sluiced by the financial crash, DHP regeared, restructured and survived.  But now as the company moves…