Lib Dem Heidi Allen will quit as an MP at the next General Election , blaming the "nastiness" of British politics.
The former Tory MP and Change UK leader said she was "heartbroken" by the decision, but had become "exhausted" from being shouted at in the street and sworn at on social media.
In a letter to her constituents in South Cambridgeshire, she wrote: "I am exhausted by the invasion into my privacy and the nastiness and intimidation that has become commonplace.
"Nobody in any job should have to put up with threats, aggressive emails, being shouted at in the street, sworn at on social media, nor have to install panic alarms at home."
She added: "Of course public scrutiny is to be expected, but lines are all too regularly crossed and the effect is utterly dehumanising. In my very first election I remember writing "I will always be a person first and a politician second" - I want to stay that way.
"So I have reluctantly come to the decision that I will not re-stand when the next general election comes."
She said she would step down whatever happens in tonight's vote on holding a Christmas election.
Her statement was published within hours of Jeremy Corbyn announcing Labour would back a vote on holding a snap poll in December.
