Mary McCullagh, 59, who was living in Fordingbridge, Hants, told Nicole Anderson she would return the cash once she inherited a fictitious £9m estate.
Miss Anderson had been referred to the practice in Bournemouth in 1997.
McCullagh, who now lives in Ireland, was found guilty of 12 counts of obtaining money by deception and one of obtaining property by deception.
Judge John Beashel jailed her for a total of five years, telling her she would be released after two and a half years on licence.
He said: “I am satisfied you carefully targeted your victims. The offences relating to Miss Anderson are particularly unattractive as you took advantage of your position as her counsellor.
“These were cruel deceptions. You told Miss Anderson you were seriously ill and you were to receive a substantial inheritance.
“These offences were committed against a vulnerable woman who regarded you as a close and trusted friend.
“For four years you and your family have enjoyed the life of Riley at your victims’ expense.
“Even when Miss Anderson ran out of money you persuaded her to get a loan to provide you with more funds.”
During the trial, Miss Anderson told the jury the therapist had encouraged her to drink as much as she wanted, saying she could have a fatal fit if she stopped.
She told the court: “It was fantastic news. Any alcoholic wants to be told that they can drink.”
The court also heard how McCullagh brainwashed Miss Anderson into believing her family were trying to section her and she should break contact with them.
The jury at Bournemouth Crown Court also heard that when Miss Anderson had begun running out of money, McCullagh moved on to a second victim, David Oliver.
The court heard how she embarked on an affair with him and tricked him into giving her £9,000, which she said she needed to fund psychological treatment for her son in America.
McCullagh, who now lives in Wexford, Ireland, chose not to give evidence during the trial.
Judge Beashel heard that McCullagh had several previous convictions for fraud and was jailed for a month in 1981.