Nikki Bella says seeing John Cena with someone else will "kill" her.

John Cena and Nikki Bella

John Cena and Nikki Bella

The 35-year-old reality star ended her romance with her former fiancé just weeks before their planned wedding date last year, but has said that despite her efforts to move on from the split, she would be devastated to see him romancing someone else.

In a preview clip for the upcoming season finale of 'Total Bellas', Nikki told her twin sister Brie: "No matter what, the next time I see him with someone it's going to kill me. I still have a long way to go, but honestly I'm ready for a new me."

Since the scenes were shot, Nikki has been enjoying dates with a number of men including Artem Chigvinstev - whom she was paired with on 'Dancing with the Stars' in 2017 - and Peter Kraus.

And recently, it was claimed 'Blockers' star John was "happy" to see Nikki moving on from their break up.

A source said: "John is happy that Nikki has moved on because the end of their relationship was extremely toxic. He has finally moved on as well and is in a good place."

The pair have "no desire to work things out right now", and sources say they've both realised they're "better off apart".

The insider added: "In the end they just both realised that they are better off apart. She made him out to be a monster and he kind of was in the end. But she harbours no hard feelings towards him either. It just ran its course."

Meanwhile, Nikki recently claimed to still be close friends with wrestler and actor John, and said she was "grateful" to have him in her life.

She said: "We're good ... as good as being apart can be. I've always been grateful to have John in my life and to have a man like that. He's an amazing man. And even through such a hard breakup, he has been truly so amazing."