Jonathan Baines, 44, also known as "Willy", was found dead at a house on Ropery Road, Gainsborough, on 1 August.
Pamela McLaggan, 51, of Greystones Road, denied murder but pleaded guilty to manslaughter.
Prosecutors accepted her plea. She was remanded in custody at Lincoln Crown Court ahead of sentencing on 21 December.
The court heard Mr Baines had been out for the day at Market Rasen races before returning to Gainsborough and visiting pubs in the town.

The move is part of national fire service reforms unveiled by Home Secretary Theresa May last week.
Sussex PCC Katy Bourne said emergency services would have an increased duty to collaborate under the new bill.
But West Sussex County Council (WSCC) said it already had an excellent model.
East Sussex's fire authority said it would co-operate with the PCC but it believed collaboration could be achieved without elaborate structural change.
Ms Bourne said she had written to WSCC leader Louise Goldsmith and Phil Howson, East Sussex Fire Authority chairman, to request they begin to look at the feasibility of bringing both fire services under her authority.
"Just as we have one police force that effectively manages the county, we need to understand if one fire service not two could achieve the same," she said.
Ms Bourne's letter met with cross-party opposition from WSCC.
And Ms Goldsmith also invited the home secretary to visit West Sussex and see an alternative to the government's preferred plan.
Ms Goldsmith said West Sussex fire service was already integrated within the council and served communities.
She added last year's Shoreham air disaster showed how West Sussex emergency services already worked together.
East Sussex Fire Authority said it was willing to co-operate with the PCC to determine whether proposals could improve delivery of services and create efficiencies.
In a statement, it added: "[The fire authority] believes whilst close collaboration between the emergency services is essential, it can be achieved without elaborate structural change.
"It is also the fire authority's considered view that it is more accountable to the community it serves because its members are elected councillors."

The Cherries went down 2-1 at Sunderland on Saturday, becoming the first team to lose to the Black Cats in the Premier League this season.
Dan Gosling's goal, which gave them the lead, was their first for three games.
"It shouldn't be down to a lack of confidence," Howe told BBC Radio Solent. "We scored six goals against Hull prior to these two games."
He continued: "A couple of weeks later, if you were to put the chances we've created together into a clip sequence, the fact that we haven't even scored one goal is difficult to take."
Bournemouth were stunned by goals for Sunderland from Victor Anichebe and a Jermain Defoe penalty and they were unable to find an equaliser, even against 10 men following Steven Pienaar's dismissal.
"We've had enough chances to win three games today," Howe added.
"Sometimes football pans out that way and you have to accept it. It's how you move on from that which is key."
A woman has admitted killing her partner who was fatally stabbed after returning home from a day at the races.
[NEXT_CONCEPT]
Plans set out by the Sussex police and crime commissioner (PCC) to take responsibility for fire services in East and West Sussex - and potentially merge them - have met with opposition.
[NEXT_CONCEPT]
Bournemouth boss Eddie Howe admits his side's sudden lack of confidence in front of goal is "baffling".