Myleene Klass has hit back at a troll who suggested her boyfriend will cheat on her.

The 42-year-old star - who recently celebrated the fifth anniversary of meeting PR guru Simon Motson - responded on Instagram to a cruel message from a follower, who said her man was going to be unfaithful.

Commenting on a loved-up post from the happy couple, the troll wrote: ''Not long before this one cheats on you. Dear oh dear, heading for the lawyers are we?''

In response, Myleene quipped: ''He wishes! Cheating exes usually get a house, a car and a fat pay-off!''

Myleene's reply appeared to be a reference to her ex-husband Graham Quinn, who left her on her 34th birthday in 2012 after six months of marriage.

However, it's never been confirmed he was unfaithful.

The former Hear'Say singer - who has daughters Ava, 13, and Hero, nine, with her ex - recently admitted she thought she'd ''be a single mum forever'' following her divorce.

However, she's since found love again with Simon, and the couple welcomed their son Apollo into the world 12 months ago.

Myleene admitted: ''This is new for all of us, there's been massive changes in my life. I thought I was going to be a single mum forever.

''The first shock of being a single mum was horrible. It's not a blueprint I recognised, when I got into the role of a single mum, I had the fear of, 'How am I ever not going to be a single mum?' I really like how this flows.

''I really love me and my girls, it feels like it's us against the world. I love that we go everywhere together, I love that they're my three amigos, it's a really lovely feeling.''