A MUM was sending “explicit sexual messages” to an Irish lover behind her husband’s back before she vanished off a cruise ship, it’s claimed.

Cops believe Xing Lei Li, 38, may have been killed and thrown overboard in a suitcase while on holiday with hubby Daniel Belling and their two young children.

The Chinese national hasn’t been seen since February 10, 2017 — the day after the family boarded a ten-day MSC Magnifica cruise of the Mediterranean.

Murder suspect Belling claims she walked off the ship in the Greek port of Katakolon after a row — despite the cruise operators insisting its electronic systems would have picked this up.

His lawyer has now unearthed bombshell new evidence showing Xing’s credit card was used to pay a toll on Dublin’s M50 after she disappeared.

And it’s emerged the locks on their Dublin house were changed — while Belling was sitting in an Italian prison as cops probed the baffling case.

Lawyer Luigi Conti yesterday blasted officers for failing to consider that Xing might still be alive as he revealed they had discovered she had “a lover”.

He said: “On her mobile phone there were messages, explicit sexual messages, showing there was an extra conjugal relationship. The mobile number sending the messages was an Irish number.

“I just find it astonishing, that from the right beginning, they only believed her, to be dead. They never went looking for her.”

Computer programmer Belling was lifted as he tried to fly home from Rome’s Ciampino Airport with their kids after the cruise on February 22, 2017.

He was released last April and is now living back in Clarehall, Dublin, with his children and his Chinese mother-in-law while the probe continues in Italy.

She has defended him as “a very good person”, telling an Italian TV show: “I don’t think he could hurt my daughter.”

Solicitor Conti said the case is due to go to trial in March and claims evidence obtained by Belling’s nephew should be enough to exonerate him.

He told the Irish Sun: “An invoice was sent to us in the post by Daniel’s nephew. It showed her credit card had been used to pay the motorway close to Dublin after Daniel was arrested.”

Conti said the M50 toll was paid on March 21, 2017. He continued: “While Mr Belling was in prison, I was given back his house keys. Daniel’s nephew went to the family home and then called me.

“As he found out that he could not open the house with those keys, I advised him to call the police and check with them, if there had been any kind of measures.

"Nothing had been carried out or was done.

“Together with the police, Daniel’s nephew opened the door. The house was in order. No one had broken in.

“It was clear, that someone entered the house and changed the locks. The wife had a set of keys. According to her husband, she was the only one to have copy of the keys. She entered the house and then changed the lock.

“The nephew, once he managed to enter the house, changed the locks, but he did it officially in this case.

“Daniel, now lives in the same family home, close to the airport, with his two children and his mother-in-law."

He added: “If she was in doubt he had killed her daughter, she would have nothing to do with him.”

Conti said it was baffling cops had spoken to “300-400 witnesses” who “did not notice anything unusual” — and told how officers failed in their probe.

He said: “Mr Belling’s cabin was not seized. Therefore, Italian forensic police got onboard the ship seven days after the ship had docked at port as the final destination, to find the Bellings’ cabin had been reassigned to another couple.

“The police took some photos from Belling’s balcony. In the hypothesis he had killed his wife, he would have had to throw the suitcase for at least 13m away, for it to reach the sea.”

And Conti said there could have been an “error” registering Xing as she fled the ship while it docked.

He claims Xing, who ran a wedding planning firm, had told a psychologist in Ireland that she was “fed up with her kids” and was “tired of Europe”.

Belling has claimed he was “set up” by his “cruel” spouse. The Italian prosecutor’s office could not be reached for comment on Conti’s claims.