In her new book "Remembering Whitney," Whitney Houston's mother, Cissy, writes about the shock, hurt and confusion she felt when she found out that Whitney and her brother Michael did drugs together. Oprah talks to Cissy and Michael about the drugs that ultimately cost Whitney her life. "I feel responsible for what I let go so far," says Michael. "It just got out of hand." "Watch Oprah's interview with Cissy and Michael Houston on "Oprah's Next Chapter" on Monday, Jan. 28, at 10 p.m. ET on OWN.