Husband's grubby sex with colleague

MY husband is infatuated with a younger colleague.

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She’s all he ever talks about. I’m constantly being told how sexy, clever and sassy she is.

They work for a large firm. She's a rising star who is destined to go places. I'm convinced she's using him while she learns the ropes and will drop him as soon as someone more glamorous and influential comes along.

My friend (who works in their post room) has warned me that it's an open secret that they sneak off for smutty sex in disused offices when the coast is clear.

I feel humiliated and redundant. How can he stand to treat me like this?

At weekends he’s like a caged animal because he can’t see her. He stomps around the house in a mood then creeps down to the garden shed to make secret calls.