The mother of late billionaire Bruce Wasserstein’s love child is battling in court to let the little girl visit his sprawling East Hampton estate. Erin McCarthy, who got knocked up by the mogul while he was married to third wife Claude Becker, sued in Manhattan Surrogate’s Court for an order allowing daughter Sky Wasserstein, 5, to spend time at Bruce’s former seven-bedroom mansion on 26 acres. In court papers, McCarthy, a Columbia business school grad, says she consulted a child psychologist following Wasserstein’s sudden death in 2009, reports The Post’s Julia Marsh. The shrink “explained that it is important for a child who has lost a parent in infancy to be exposed to concrete representations of the lost parent,” McCarthy wrote. But McCarthy says Wasserstein’s older kids have banded against Sky “because she was born out of wedlock” and barred mom and daughter from the house. Becker, however, with three of Bruce’s grown kids, portrayed McCarthy as a nut job who broke into the manse shortly after Sky’s birth, carrying her newborn and screaming obscenities. Becker claims the incident traumatized her and Wasserstein’s two teenage sons. Judge Nora Anderson wouldn’t rule on McCarthy’s request, saying it was “inextricably intertwined” with how Wasserstein’s properties are being divided. A hearing on that matter is set for September.