Ms Pearce fears she will lose custody of her two young sons
A British mother's conviction for adultery has been upheld by an appeal court in Dubai, the Foreign and Commonwealth Office (FCO) has said.
Marnie Pearce's sentence was reduced to three months, she was fined 3,000 Dirhams (£593), and will be deported.
Ms Pearce says her husband accused her of adultery so he could gain custody of their two children, a claim he denies.
She told the BBC the sentence was effective immediately and she was certain she would lose her children.
'Lost my children'
Speaking from Dubai, Ms Pearce, 40, who is on bail and was not present at the hearing, said: "I know I'm going to prison… when they catch up with me."
"I'm going to prison, what more can I say about it... I've lost my children, I just need somebody to do something for me."
She said she intends to appeal the decision to a higher court. Before the appeal court reduced her sentence she had been facing six months in prison.
Ms Pearce, who is originally from Bracknell in Berkshire, was convicted of adultery in November.
She denies the adultery claims made by her ex-husband, Egyptian national Ihab El-Labban.
They had two children together, aged four and seven.
She first met her ex-husband in Oman and married him in the Seychelles in September 1999.
They moved to Dubai but the relationship eventually broke down.
In March last year she was arrested and accused of committing adultery with a British man who she insists was only a friend.
She contacted Bracknell Conservative MP Andrew MacKay, who has raised her case with Foreign Office Minister Lord Malloch-Brown.