Peter Morgan, 54, of Llanellen, Monmouthshire, is accused of strangling Georgina Symonds, 25, in January 2016.
The father-of-two admits the killing but denies it was murder.
On Friday, Newport Crown Court heard he had been divorcing his wife and would have given her half his property empire so he could be with Miss Symonds.
The court heard Mr Morgan said in a police interview: "I love George. I gave everything up for her. I've been married for 22 years so I gave up my marriage for her.
"I was in the process of giving up half my properties and companies to my wife to be with her.
"She was my life."
Mr Morgan described himself as a "Sugar Daddy" who lavished Miss Symonds with expensive gifts and paid her up to £10,000 a month to be his personal escort.
He said the former burlesque dancer from the Allt-yr-yn area of Newport was "perfect" and praised her figure.
But he said she struggled with bipolar disorder and had anxieties after the suicide of her former boyfriend.
He said: "She got very anxious with her ex. He texted her and just wouldn't let it go."
Mr Morgan said she was taking cocaine and drinking and claimed he once found her in the bath in a "half attempt" to cut her own wrists.
He said: "She was under the water and I pulled her out. After the death of her ex, she was taking drugs and drinking regularly.
"She was blaming me for his death. She was making me feel guilty and saying it was all my fault."
He added: "I wasn't plotting this for days or weeks. It definitely was not a case of me wanting her dead. I don't know why I wanted to kill her."
Previously, prosecutors said Mr Morgan murdered Miss Symonds after he found out she was going to leave him as soon as he signed one of his homes over to her.
He admits strangling the mother-of-one with baling twine from his farm, then wrapping her body up in black plastic and hiding her in a workshop behind his farmhouse.
But he denies murder because of diminished responsibility due to Asperger's syndrome.
The trial continues.
A millionaire accused of murdering his escort lover told police he had been ready to split his £20m fortune to stay with her, a court has heard.