DEAR DEIDRE: When my partner’s ex found out I wasn’t able to go on holiday with him and his kids, she muscled her way in instead.

He’s agreed to it, and I’m furious. I’m really uncomfortable with the arrangement, yet he expects me to be OK with it.

I’m 40 and my partner is 48. His ex-wife is 47, and their daughters are 15 and 13.

The girls live with my partner, which means they only see their mum on alternate weekends.

I’m more of a mum to them than she is, if I’m honest.

It’s the elder girl’s 16th birthday in November, and my partner has booked a week in Tenerife for her and her sister to celebrate.

As it’s in term time, and I work in a school, I’m unable to go. It’s too expensive to go during the school holidays.

The girls must have mentioned this to their mum because the next thing I knew, she’d muscled her way in on the holiday.

She says she’ never gets to spend quality time with her girls, and this is the perfect opportunity.

My partner doesn’t want her to go but has reluctantly agreed.
And to make matters worse he’s paying for her.

I’m not jealous or worried anything might happen between them. He finds her exasperating and has told me he wished he’d never married her – although he loves his girls.

But I think it’s totally inappropriate.

Am I wrong to feel this way?

DEIDRE SAYS: Your feelings aren’t unreasonable at all. Few people would be happy to wave their partner off on holiday with their ex, when they wanted to go.

However, you need to think of the girls’ feelings here too. It might be good for them to spend a week away with their mum.

And if you try to stop her going, they would probably resent you terribly.

If possible, see if you can go out to join them for a weekend while they’re away.

Talk to your partner about how you feel, so he can reassure you. Ask him to always check in with you regarding his ex – so that you can make decisions as a couple in the future.

Being a stepmum is never easy. My Stepfamilies support pack has more information and sources of help.