He also sent an email to his wife apologising for his actions and admitting he had been ill for a long time and had "destroyed himself".
The inquest heard Mr Todd, a father-of-three from Halam, Nottinghamshire, had visited suicide websites and had aborted one attempt at suicide shortly before he died.
Det Sgt Kevin Evans said he had been through Mr Todd's mobile phone and email records and had identified significant messages to people, referred in the hearing only by a letter at the coroner's insistence.
Mr Evans said Mr Todd had admitted to his wife Carolyn having an affair with person A on Thursday 6 March, a few days before his body was discovered.
The police chief spoke to A the following day saying it was a "nightmare scenario" and he needed a "week to sort his affairs and then he would kill himself", and asked A to obtain sleeping pills.
Carolyn Todd spoke outside the inquest
He sent further messages to B, a Metropolitan Police employee, and C, apologising for "being a pain" and used the internet to look up methods of carrying out suicide before sending a message to person D saying he was "fed up and not in a good place".
On Saturday 8 March, he bought guides to the Lake District and north Wales, and sent a text to his deputy saying he intended to take Monday off work.
Mr Todd sent a further text in the evening to G saying he was "in a dark place" before spending the night at his Manchester city centre flat with G.
When G left on Sunday, Mr Todd "appeared anxious, he was crying, like a man who had lost everything".
A text to B sent on Sunday read: "Not your fault.... remember the good times". He also emailed his wife apologising for his actions.
Later that day, he sent a further series of messages from the Cumbria area, ending in one to C just after midnight saying he intended to "end it all" but had "bottled out".
Moments later he sent another to C which read: "Just got back from the lakes. Really fell out with Carolyn but will try to sort it out tomorrow."
His mobile phone signal was tracked to the Menai Straits area at about 2300 GMT on Monday 10 March, and his body was discovered the following day.
Following his death, revelations concerning Mr Todd and a number of extra-marital affairs emerged.
Mrs Todd was at the inquest but was not one of the witnesses. She was expected to give a statement at the end reaffirming her love for her husband.
In a narrative verdict, coroner Dewi Pritchard-Jones ruled Mr Todd died of exposure when his state of mind was affected by alcohol, the sleeping drug Nytol and confusion due to his personal situation.
When the inquest was opened and adjourned in March, it heard there were no injuries on Mr Todd's body.
It was fully, although lightly, clothed and over the blood alcohol drink-drive limit.
Mr Pritchard Jones was also told there was no evidence Mr Todd had jumped or fallen as there were no external or internal injuries or scuff marks on his "sturdy" mountain boots.
Mr Todd, who had been tipped as a future Metropolitan Police commissioner, was appointed chief constable in Greater Manchester, England's third largest force, in October 2002.
He had been a police officer since joining Essex Police in 1976.
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