John Cena has opened up on "vulnerability" and ignoring his critics amid his difficult breakup from Nikki Bella.

John Cena and Nikki Bella

John Cena and Nikki Bella

His former fiancee appeared to signal the end of their relationship last month - after they initially split earlier this year before trying to make it work - and now the 41-year-old WWE star has cryptically hit out at the haters.

He tweeted: "Be vulnerable. It shows you for you. People will judge, disagree, and downright despise. But you will be you.

"Most of those who judge, disagree, or despise do so because they struggle with vulnerability themselves."

The words of wisdom come just over a week after Nikki, 34, admitted their romance was "officially" over.

She told PEOPLE magazine: "After I called off the engagement, we tried to work on our relationship to get back to where it was, and in order to move forward with our wedding.

"After much time and soul-searching alone and together, we have decided to officially part ways.

"I had a beautiful and loving 6-year relationship with a wonderful man. I have the utmost respect for John, but I know this is what's best for me."

Despite her comments though, the former flames have reportedly been spotted on holiday together since she released her statement.

Although they're adamant they're just "friends" now, it seems behind the scenes they're determined to make things work after enjoying a mini break in Lake Tahoe.

The on-again off-again couple raised eyebrows when a fan bumped into them and reportedly requested a photograph with them but, while John beamed in the shot, Nikki abruptly turned round so she couldn't be seen, according to The Blast.

The publication added: "Later that weekend, the couple was seen at a fancy dinner with Nikki's whole family ... and the two appeared to be far from broken up."