Wife’s depression

My wife can suffer long bouts of depression that Center on where her life is and what she’s missed out.
She feels her weight caused her so many problems growing up and her housebound current state means she can’t do anything.
She has alienated friends and family and I’m not enough to make her not feel lonely.
She treats the depression with huge food binges that help at that moment but leave her disgusted afterward so she eats again.
She really needs an understanding friend