McDermott and Tori Spelling have been married for seven years and are the parents of Liam, 6, Stella, 5, Hattie, 2, and Finn, 16 months. The family has starred in several TV reality shows together.
"I am truly sorry for the mistakes I have made and for the pain I've caused my family," McDermott told UsMagazine.com in a statement.
"I take full responsibility for my actions and have voluntarily checked myself into a treatment center to address some health and personal issues. I am grateful to be getting the help I need so I can become the husband and father my family deserves."