"Kim has been to rehab more than once before," says the source, "but every time is a new time, and everyone just hopes this sticks and that she gets the help she needs. It's serious."
Richards has been "erratic. Everyone was really worried about her," says the source, who adds that Richards is not living with Ken, the boyfriend who was introduced as her love interest this season.
During a recent episode of the Bravo show, Richards says she's planning to move in with Ken, and cameras show her packing up her belongings.
"He's not in the picture. No one really knows what the deal was with them, but Kim doesn't live with Ken," the source says. "She's basically homeless, staying with various friends. She doesn't have a home base. It's not unusual for people to not hear from her for long stretches of time. It's been that way for years."
"Her family is relieved she's getting help," adds the source. "She has lots of issues. She needs help."
Viewers have watched Richards' increasingly bizarre behavior and slurring of her words this season, which had been attributed at least in part to her taking anti-anxiety and antidepressant medications, along with an anti-seizure medication which can be used to treat alcoholism.
Richards is receiving well-wishes from some of her colleagues since seeking treatment. Castmate Taylor Armstrong threw her support to Richards this week, telling Andy Cohen Monday night on his Bravo talk show Watch What Happens Live: "I adore Kim and I stand behind her. And if there's anything I can do to support her [I will]; but if she's getting healthy what more could we ask."