Just like her sister, Jamie Lynn Spears's lovelife implodes amid allegations her fiancé cheated

Britney Spears' little sister Jamie Lynn cut a sad figure yesterday as she stepped for the first time following allegations her fiancé had cheated on her.

The 17-year-old actress's relationship was been rocked by claims that Casey Aldridge, 19, had been having an affair with Kelli Dawson, 28.

After the revelations last week, the Zoey 101 star and her two-month-old daughter Maddie Briann have fled the couple's home in Mississippi to stay with her mother Lynne 30 miles away in Louisiana.

Holding the baby: A miserable Jamie Lynn Spears clutches her baby Maddie close as she shops in Kentwood, Louisiana

Pictured for the first time since the reports, Jamie Lynn looked miserable as she joined mother Lynne and baby Maddie to buy a new mobile phone in a store in her hometown of Kentwood.

Dressed for the hot weather in a denim mini skirt and white vest, Jamie Lynn was still wearing the engagement ring she accepted from Casey in March - just three months before their daughter was born.

The couple, who have been dating for two years, were expecting to wed later this year, but their marriage plans have been thrown into jeopardy following the recent reports.

Kelli told America's InTouch Weekly magazine she had been dating Casey since November 2006 and had still been seeing him when Jamie Lynn was six months pregnant with Maddie - the same month he proposed.

Three generations: Jamie Lynn is being helped to care for baby Maddie by her mother Lynne

Kelli told the publication: 'I see him all the time, at least once a week.'

She claims she stopped sleeping with Casey towards the end of Jamie Lynn's pregnancy.

She said: 'It just didn’t feel right. He had to deal with the baby coming, and it had to stop.'

Britney's first husband Jason Alexander, who still lives in the Spears' family hometown, supported Kelli's claims.

'The other woman': Kelli Dawson claims she had an affair with Casey Aldridge while Jamie Lynn was pregnant with Maddie

Coupled up: Kelli Dawson pictured with Casey Aldridge

He said: 'Kelli and Casey have been a couple on and off for a few years.

'They were a really tight couple, but I think it was hard for Kelli, having Jamie Lynn in the picture.'

Casey has denied the allegations, accusing his ex-girlfriend of fabricating the affair to make money.

If Jamie Lynn needs lovelife advice, she can turn to older sister Britney, who has two failed marriages behind her.

She is currently getting her career back on track after a tumultuous two years following the collapse of her two year marriage to aspiring rapper Kevin Federline.

Trouble? A pregnant Jamie Lynn with Casey Aldrige earlier this year