EastEnders exposes Callum Highway’s affair with Johnny Carter next week, when Phil Mitchell catches them in the act – and turns violent.

Despite fighting their mutual attraction, the pair continue to be drawn to one another – but after Phil spots them in a passionate clinch, will he tell Ben about his husband’s betrayal?

“Callum recently cheated on Ben and spent the night with Johnny,” our Walford spy reminds us.

“But the morning after, he was consumed by guilt and insisted they can only be friends. However, despite Callum’s protests, it seems that they can’t keep their hands off each other…”

While it was Callum who ended their brief fling, he gets jealous when he learns that newly-single Johnny had a one-night stand.

Jealous at the thought of Johnny being with someone else, Callum acts on impulse and they soon end up back in one another’s arms.

But Phil later walks in on the pair’s secret liaison after Linda invites him round to The Vic, and is naturally furious. He lunges at Johnny and attacks him, and it takes Callum, Jay and Billy to pull him away.

“Phil is having a rough week, following Julie’s plans to take Nigel away,” explains our insider.

“So finding out that Callum is cheating on his son really is the final straw. He explodes in a bitter rage, and poor Johnny bears the brunt of his anger.”

Callum later calls round to try and make amends with Phil, begging him not to tell Ben and Lexi about his disloyalty. But Phil’s still raging at Callum for breaking his marriage vows, and refuses to even hear him out.

Jay is forced to step in to calm the situation, but this leads to a nasty argument that could divide the family for good.

With the Mitchells well and truly at war, will Ben discover the truth about his husband’s infidelity from his prison cell?