Bob Cole, 68, committed suicide at 2pm at the Dignitas euthanasia unit around 18 months after watching his wife Ann Hall do the same.
Mr Cole, who suffers an aggressive form of lung cancer called mesothelioma, said he was "taking a stand" and urged politicians to review the law, which makes it illegal for others to encourage or assist someone trying to take their own life.
MPs will vote on plans meaning two doctors could independently confirm a patient was terminally ill and had reached their own, informed decision to die.
Mr Cole told The Sun: "I should be able to die with dignity in my own country, in my own bed. The law needs to change. How do you change the law? People have got to take a stand. So that's what I'm doing today.
"I saw Ann die and a year later to be faced with the same decision yourself is quite the double whammy. I had just started to pick myself up when I fell ill."
But his decision has been criticised by Christian campaign groups.
James Mildred from the charity Care, which opposes a change in the law, told Premier's News Hour: "Cases such as this are incredibly tragic and they do commend to us a compassionate response but we have to be careful about putting them in a correct context as well.
"MPs have a duty to remain as objective as possible."
He added: "The impression that is given in much of the media is that there are many people seeking to end their own lives but the figures tell a very different story.
"Since 1998 until 2014 just 273 people went to Dignitas."
Mr Cole said his cancer had seen him bent double, "crouching like an animal", adding: "That's no life."
In asking MPs to be "sympathetic", he told the Sun: "The politicians need to have the guts to change this law. Just bite the bullet. Accept that the British public want this change. If they don't it will be forced upon them because the public feeling is overwhelming."
His wife, Ann, 67, who suffered from progressive supranuclear palsy, chose to die in February last year, in a process Mr Cole called "graceful".
Canon Rosie Harper, chaplain to the Bishop of Buckingham, told Premier Mr Cole's case was "an extremely strong argument for changing the law in this country".
She said it was clear he had to end his life earlier than he would have needed to because he had to be well enough to travel to Switzerland.
Canon Harper said Mr Cole had seen his wife "peacefully and beautifully" pass away at Dignitas.
"She knew what the other possibilities were, maybe somebody in their family or friends and she'd watched them die and because of that she made her decision and because of that he made his decision.
"He knows what the alternatives are."
Responding to the argument that only God can decide when someone dies she said: "I just don't believe in a God who micromanages our life like that.
"I think that he's given us our lives as a good and free gift and all through our life we make all sorts of life choices.
"I don't think he'll stop you making the choice at the moment when you most need your freedom and say 'I'm very sorry you may think you need to die now because it's unbearable, but I'm going to let you suffer for another two months.'"