The former White House intern was so depressed that she underwent lengthy therapy to try to come to terms with the termination.

But she had become pregnant by another man with whom she had a relationship during the time that she and the president were lovers and she never told Mr Clinton about her abortion.

Miss Lewinsky's secret is revealed in the book Monica's Story, by Andrew Morton, which is being serialised in The Mirror newspaper.

She says: "I wasn't emotionally prepared for it. It was just horrible and very depressing."

Her other boyfriend - a Pentagon official called Thomas - had been seeing other women. When she found out, in the second half of 1996, she split with him - then discovered she was expecting, Mr Morton says.

Children sadness

Miss Lewinsky loved children but had wanted to wait until she was in a long-term relationship to have them. Not wanting to be a single mother, and still in love with the president, she opted for the abortion, The Mirror reports.

"It proved to be noisy, painful and distressing, leaving her traumatised and deeply scarred," the book says.

Her family and friends were worried about her emotional state. One friend, Neysa DeMann Erbland, said: "It was a very difficult time for here, especially as she wanted kids so desperately."

Finally, Miss Lewinsky was ordered by her mother Marcia to have counselling in a Virginia medical centre.

Over a series of sessions, she talked in detail about her experiences. The therapist found her "anxious, depressed and with low self-esteem".

Miss Lewinsky, 25, had grown up feeling insecure due to a combination of her size and her parents' acrimonious divorce.

Her problems were still unresolved when her therapist left the clinic.

Pentagon move

It was then that she found herself confiding details of her affair with the US president to colleague Linda Tripp - who secretly recorded their conversations which formed the basis of the case against Mr Clinton.

Miss Lewinsky had moved with her mother to Washington when she was only 22 and got a job in the White House. Staff there moved her to the Pentagon after the affair began, suspecting she and the president were too close.

It was at the Pentagon that she met Thomas. Her friends hoped that relationship would put an end to her illicit affair - but the attraction between Mr Clinton and Miss Lewinsky proved too strong and continued into 1997.

She even teased the president about Thomas to make him jealous, the book reveals.

In her first British interview, she told the Mirror newspaper: "I feel excited that after this 14-month nightmare, people are now getting introduced to the real Monica.

"My book's coming out and people will understand what I had with the president wasn't just a sexual servicing contract. It was so much more than that. For me, it was a love affair.

"There were times by the way he held me, stroked and talked to me, that I thought he was in love with me, but now, well, I don't want to put words in his mouth."

Jealous and sorry

Asked about her feelings towards First Lady Hillary Clinton, Miss Lewinsky said she was jealous because she was the wife of her lover.

Hillary Clinton: her husband considered divorce

"Their marriage is an enigma to me. I could understand if Mrs Clinton hated me. I don't know if she does, but I don't feel it's all down to me. He was controlling it.

"But it's a woman's tendency as emotional Band-Aids to blame the other woman and that is what she has done, blamed me more than her husband, which is not necessarily appropriate in this case."

Miss Lewinsky also denies any malicious intentions towards the First Lady or the Clintons' daughter Chelsea and makes her now-famous apology.

"I do feel guilty about the First Lady. I never thought this would come out. I'd like her and Chelsea to know I'm very sorry for what happened.

"I feel worse about Chelsea. I feel horrible that she is the most important thing to her dad and it hurts me to know how much pain she must be going through because of this and I'm part of the cause."

She also says Mr Clinton had told her he had considered a divorce 10 years earlier. He was having affairs then, but decided it would be better for the family to stay together.

In the interview, she also fondly recalls her favourite memories of the president and describes some of their most tender moments in his Oval Office study, often just talking and telling jokes.