Sarah Howden: Celebs have forgotten sisterhood rules about avoiding married men

OH, how I used to like you, Angelina. Cool, edgy and non-conformist, you were the antithesis of the girlie girl. But you had your morals and your beliefs. Then along came Brad.

It didn't take long for poor Jennifer to file for divorce after the shooting of That Film was wrapped up. And it took only a couple of months before Brangelina officially became an item. Then came the baby news, confirming suspicions about the real reasons behind the demise of what was once Hollywood's hottest marriage. Claiming taking another woman's man was abhorrent – she's seen the pain her father's infidelity put her mother through – Angelina fiercely denied she was behind any marital breakdown. Until now.

Maybe it was a jet-lagged slip-up, as she's usually so careful, but during a recent interview with the New York Times, Angelina let some big news slip: they fell in love on the set of Mr & Mrs Smith . . . while he was still married to Jennifer Aniston. Ouch.

In fact, Angelina told the paper that she looked forward to showing her brood Mr & Mrs Smith, because "not a lot of people get to see a movie where their parents fell in love".

Erm, sorry Angelina? You both fell in love while he had a ring on his finger from another woman? You were both in love with one another while he holidayed abroad with his wife? Sorry to break it to you, but just because you didn't necessarily "seal the deal", it doesn't mean you weren't having an affair. It was one of the heart, and you were The Other Woman – even if it was emotionally.

I've always been Team Aniston. Sweet and down-to-earth, she's not contrived with high-profile UN missions, rainbow family plans and constant digs at her man's ex. She's just a normal woman who can laugh at herself, who fell in love and got hurt. And now, three years on, she's just trying to rebuild her life. In peace. And without having new revelations thrown in her face.

And then there's Sienna Miller. She's been slated on both sides of the pond for her topless antics – and the rest – with married actor Balthazar Getty. Surely she too must have known that getting it on with a taken man is just not on; breaking up a family is the ultimate sin against sisterhood and such antics would ruin her reputation? And yet she was seen eating the face off her still-married beau and holidayed with him. Again.

It's clear something has happened in celebsville – they've forgotten the sisterhood rules of staying away from another woman's man. It won't ever gain you respect among other females and you look, well, cheap. And as for Angelina? Get over yourself, love. Rehashing the past simply makes you look slightly resentful of his ex. And a little bit pathetic. Maybe Jennifer should be shown the same compassion and dignity that your mother was denied.