There are three people in my marriage, me, my wife and her twin sister

DEAR DEIDRE: My wife’s twin sister constantly sticks her nose into our relationship and thinks she is judge and jury.

She never misses a trick when it comes to putting me down or making sarcastic comments.

Almost all of them are about how little I do around the house and care for our daughter, who is 11.

My sister-in-law has never been able to stay in a relationship for longer than a few months and I can see why. She’s a complete pain.

I do really long hours and my wife also works full-time, so our house always has washing hanging out and DIY jobs that need doing.

Her home is immaculate but she works part-time and doesn’t have children. I’m 38 and my wife’s 35. I am so fed up with her sister.

She always has to give us her opinion, whether we have asked for it or not. She’s the self-appointed expert.

I sometimes feel as though I am in a relationship with both women. I wish she would keep her nose out of our life.

I’m sick of hearing from her – someone I don’t respect – about what I should and shouldn’t be doing.

My wife just tells me to ignore her. Last week her sister told me I needed to wash my car more regularly as it was “an embarrassment”.

It took all my strength not to bite her head off.

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DEIDRE SAYS: Your wife and her sister share a special bond but her twin seems unable to separate their relationship from yours.

She freely interferes in your married life with no concept of how it might make you feel, using the relationship with her sister as an excuse to invade your privacy.

When others criticise, remember it says more about them than you. You can’t control what she says, but you can control how you react. Rather than simmering, calmly put her right straight away or walk away. She’ll soon get the message.