Subo, 50, says she is determined not to let her wealth and fame change her way of life.
And she has no intention of going on a spending spree.
The singer said: "I know what's important to me and the money just isn't. I could shop in Waitrose every day if I wanted to. But I want to be normal."
Sony's No1 act, who was the fifth-biggest-selling recording artist in the US last year, still lives in the council house she grew up in with her parents and nine older siblings, on Yule Terrace in Blackburn.
She bought a £300,000 five-bedroom house in the West Lothian village but returned to her old home to have a normal life away from the spotlight.
Susan laughed: "Why would I want to live in a castle? It'd be draughty.
"There's so much empty space in that new house, it made me feel lonely.
"There were different neighbours. So much toffee hanging off them, I was looking for the apples. It was too quiet."
She added: "I did have my house decorated. It looked a bit shabby before, I can tell you. The decor was 50 years old and there were 10 of us - my mum, dad, me, the others and Betsy Bagpuss, the cat.
"It was a big fat thing that ate everything. It had a mad passion for crisps, any flavour. As soon as it heard the bag rustling, it was on your lap."
As well as family photos on the walls, Subo's home is awash with pictures of the Virgin Mary, Joseph, Jesus and little cribs.
She is planning a trip to Knock, in Ireland, on a pilgrimage for her dead mother and her beloved sister Kathleen, who died 11 years ago.
She said: "It's a private thing. I go to Mass and confession. When you are a celebrity, everyone wants a piece of you.
"But in Knock, I'm one of the crowd. My faith is the backbone of my life. It has kept me on an even keel and given me solace."
Susan, who revealed the terrible bullying she endured as a child in her autobiography, The Woman I Was Born To Be, says she has long forgiven those who picked on her and even used their mean spiritedness as an inspiration.
She said: "Every time I sing the song You'll See, I think of that and all the other people who thought I would never amount to anything.
"I'm stubborn. I was determined to prove them all wrong. I knew my time would come. Those bullies have apologised. They've grown up. I think they have finally accepted me for who I am.
"I don't bear grudges, which is lucky. Celebrity means you are on television, that's your job, that's your service. But I've learned I can do that and then come back and be normal. Living in my old house, where my parents brought me up, keeps me grounded, reminds me who I am.
"If you lose your roots, you've lost your identity. When you're on stage, everyone wants a piece of you. It's easy to be swept along, easy to lose your footing. Most artists, at some point, crack up."
Having booked into The Priory after coming second on Britain's Got Talent, Susan revealed the reasons behind the meltdown had been straightforward.
She said: "There were 50 camera crews camped out in the street. It was gushing down with rain and there were paparazzi outside trying to catch me through the windows in my night-clothes.
"They were jumping the fence. It got to the point I felt scared to go to the toilet in case they were down there. Once, I went out with a sheet over my head.
"I felt like an observer, someone who was watching a film of their life, looking in from the outside.
"You don't have time to think or process anything when things happen as rapidly as that. You just go through the motions. At the beginning, nobody explains why things are done the way they are, so you just do what you are told.
"Then after a while, it becomes clearer and you are more in control. I wasn't in control in the beginning. I got angry and het up.
"It happened because I was frightened. I did things wrong. turned into the Incredible Hulk, needed a blanket over my head calm me down. I think it was nerves that set me off, and bad temper. I needed to calm down." I k, d to ."
Her new album, Someone To Watch Over Me, is out next Monday. While the album release is likely to add to Susan's wealth, she has asked manager Andy Stephens to make sure most of the cash is invested wisely.
She is also considering setting up a foundation to stop bullying in schools. Susan said: "Maybe I will at some point, but it's a big step.
"My big phrase is baby steps, take it all slowly. Though I have heard there is a zero-tolerance-forbullying campaign in schools which I'd like to support."