Now his family in Clondalkin are rallying around to help him cope with the demands of little Luke and Carmel, as well as their 13-month-old sister Aoibhe.
"One minute you are so excited because your babies are being born, and the next your partner has died. There's no way to describe that," heartbroken Gerard explained.
Neither Gerard nor Carmel's families are sure what happened to cause the tragic mum's death and are awaiting the coroner's report.
Gerard's mother Anne, from Neilstown, has also found herself busy helping with the twins, but says she does it happily in memory of Carmel
"I'm a mammy again," said the grandmother of eight as she cradled little Luke and watched Carmel sleeping.
"At the moment it's five feeds a day for Luke and Carmel and we're really only trying to get a bit of a pattern established," Anne explained.
"Their mammy was loved by everybody, she was a very bubbly person. She was like a daughter to me and she used to be here all the time," she added.
"We've just been in shock over the past eight weeks. I'm doing this for Carmel now, we'll keep together and we'll keep strong," said Anne.
Gerard and Carmel, who was originally from Belmullet, Co Mayo, met in Crete 12 years ago. Carmel then moved to Dublin and the pair lived in an apartment in Clondalkin.
But Gerard has moved back to the family home and has given up work to take care of his children.
He spoke of how his emotions turn back and forth since his partner Carmel's sudden death.
"I'm just devastated. That's it really. The twins and Aoibhe are keeping us all busy though. We have gained so much and yet lost so much that our emotions are everywhere," he told the Herald.
The twins had to stay in hospital for eight weeks after being born so prematurely.
"They weren't even due until December. It is a full-time job looking after them," said Anne.
During the pregnancy Carmel and Gerard had decided to name a twin each, with Gerard naming the boy and Carmel naming the girl.
"Gerard picked out Luke for the little boy, and Carmel kept changing her mind, so in the end Gerard picked the name Carmel after her mother," said Anne.
She told of how the community has rallied around the family, organising fundraisers and helping out as much as possible. A night in the Coldcut Club, Ballyfermot, on Saturday raised €5,000 for the family to help with the children.
"Everybody has been just so supportive. It has overwhelmed us all.
"The people of Neilstown and Clondalkin are just fantastic," Anne said.
Both families are now awaiting word from the coroner to find out what how and why Carmel died.
"It is a waiting game now to find out what happened. The coroner hasn't been back yet and we were told it could take up to five months," said Anne.
A spokesperson for the Coombe Women and Infants University Hospital in Dublin said it is committed to act in the best interests of each of its patients at all times.
"As patient welfare and privacy is top priority at the hospital, it cannot comment on, or discuss details of individual patients," they told the Herald.
"The Coombe Women and Infants University Hospital can confirm a maternal death took place at the hospital recently which has been referred to the coroner.
"On behalf of the board, management and staff at the Coombe Women and Infants University Hospital, the Master, Dr Chris Fitzpatrick, extended sincere sympathy and condolences to the family involved."
Each year over 9,000 babies are delivered at the hospital. Out of a total of 103,995 births at the Coombe in the last decade, there have been five maternal deaths, none of which were directly related to pregnancy.
The hospital said it would be making no further comment at this time.