After partying hard on New Year’s Eve, David Arquette checked himself into rehab in California on Saturday, a friend told The Post. The friend insisted that Arquette, 39, is trying to deal with alcohol abuse and that there’s no drug addiction. “He was drinking too much,” the friend said. “Once he drank too much, he became somebody he didn’t like.” The actor has been struggling with emotional problems — mainly over his October separation from his wife, “Cougar Town” star Courteney Cox, 46, the friend said.