"I really admire David and his choice to take charge and better his life," the Cougar Town star, 46, tells PEOPLE. "I love and support him."
Arquette who separated from Cox in October and is dad to their 6-year-old daughter Coco, has been having trouble managing the separation, one source told PEOPLE recently. "He's just not handling this situation well," the source said. "He's really depressed."
Arquette, 39, has not entered the rehab program for drug use, several sources tell PEOPLE.