Ryan Shelton, 29, betrayed his pregnant partner Jess Aldridge by beginning the affair with her mother Georgina, 44, while they were all living together in a family support bubble.
Speaking for the first time, Ryan, who is now living with Georgina, told MailOnline: 'I don't care what everyone thinks, I am in love with Georgina and I don't care who knows about it.'
He said: 'Other people's opinions don't bother me at all. I know what's happened.
'There are two sides to every story and I know the truth behind all this. Not everyone will like what's happened but it's none of their business.'
Ryan and Jess, 24, moved in with Georgina and her husband, Eric, to the family home in Stow-on-the-Wold, Gloucestershire, as Jess prepared to have their baby.
Within weeks of moving in, Ryan had begun an affair with the grandmother-of-six who he left Jess for two days after Jess came home with his newborn son, Reuben.
Ryan, who works as a car parts salesman added: 'They know what has gone on here. There's more to this story than you think but that's all I want to say.'
Jess told how she felt 'betrayed' by Ryan and her own mother as they drank vodka in the kitchen together and flirting while she sat heavily pregnant watching television with her father.
Meanwhile a neighbour who dated Ryan before he met Jess has labelled him a 'serial womaniser' and 'an idiot'.
Ryan's former girlfriend told a friend that he treated her appallingly, cheating on her before she dumped him for being unfaithful.
She told the friend: 'He is a serial womaniser.
'He treated me really badly. He is a bloody idiot. When I finally saw sense and told him I didn't want to see him again, he'd drive round to my house and sit outside for hours at night in his car.'
The family friend told MailOnline that Georgina's husband, Eric, is 'devastated', having only renewed their marriage vows two years ago 'to show their continued commitment to each other'.
They said that recently Georgina had taken more of an interest in her appearance, wearing short skirts and low-cut tops as she looked like 'mutton dressed as lamb'.
'Georgina must have lost her mind,' they added. 'I think she's been flattered by the attention of Ryan, who is a fairly attractive young man, and she's let herself be swept off her feet.
'I'm not in the least bit surprised by Ryan splitting up the family, though. He is a nightmare.'
She added: 'Poor Jess at that time had no idea. She must be hurting like hell.'
