If she is given a custodial sentence, the Speaker of the House of Commons could trigger a recall petition which could result in a by-election for the seat that was previously held by Keith Vaz.
Webbe said she was “deeply shocked” at the verdict and intended to appeal.
The MP claimed she had only spoken to Ms Merritt out of “courtesy” to warn her not to breach Covid rules by meeting her partner during lockdown.
In a statement issued after the verdict, she said: “I was deeply frustrated that my partner and my accuser had been socialising in the middle of the Covid pandemic, contrary to the rules and all health advice. I was frightened and frustrated by his behaviour.
“But that fear and frustration could not, and should not, have been interpreted as harassment. The recording of the call has been taken out of context.”
However, following a two-day trial Mr Goldspring rejected the argument and found Webbe guilty of the harassment charge.
Threats of sharing nude images
The court was told Webbe was jealous of Mr Thomas’s friendship with Ms Merritt, a former girlfriend whom he dated about 15 years ago.
She was accused of making a series of silent phone calls to Ms Merritt from a withheld number.
However, the court heard that the harassment had escalated on Mother’s Day 2019 when she spoke to her on the phone, called her a “slag” and threatened to send naked pictures and videos of her to Ms Merritt’s daughters.
It is not clear whether she was in possession of any images, but threatening revenge porn was outlawed following a change in the law earlier this year.
Ms Merritt reported the matter to the police in April 2019 and Webbe was warned by police.
‘Why are you still butting in?’
Despite the warning, the MP made a further 16 calls to Ms Merritt who recorded one, which was later played to the court.
In the recording that was played, Ms Webbe can be heard saying: “Why are you still butting in and getting with Lester? Why? Why? He’s not your friend. He’s with me and I don’t want you to be in touch with me. I don’t want you to be in touch with him.”
In the background, Mr Thomas could be heard shouting: “Don’t listen to her, send me a message whenever you like. Michelle, come off the phone and call the police.”
Ms Webbe then screams: “Lester, why don’t you go and live with her? Take everything and go and live with her.”
She can then be heard repeatedly shouting: “Get out of my relationship.”
Webbe was released on unconditional bail until the sentencing hearing.