To not go to the upcoming party

Are his kids 18+? Hope he stops the DIY now. She has a partner, they can pay a handyman to do it.

Assuming your dc are older now, his priority should be you over her.

Sorry but why does she need to be your friend or make mundane conversation with you. She’s there for her child not you. She smiled, acknowledged you? What more do you want her to do? Or are you just reading more into this? TBF you must have been starting at her to notice her ‘talking about you and looking you up and down’ she’s probably thinking why does she keep staring at me!! 🤣 She’s doesn’t need to have anything to do with you, she’s civil to her ex DP because of her child not because she’s ‘wants him’. If your serious about DP then your gonna have to grow up and go along to events like this, you will never win if you try and make him chose between you and her as she will always have one up on you (his child, which is probably what you are actually jealous of!)

Well off course she's really happy; she's got a lovely new partner, and the ex on speed dial! As long as her ex doesn't get a new woman in his life, she probably believes her ex might even still have feelings for her? "Well he does come running every time a job needs doing, so ...?" She has 2x main men in her life, and you are competition. A classic case of 'I don't want him, but I don't want anyone else to have him'.

Could her behaviour be down to feeling worried that you are going to be part of her children's lives as opposed to you being part of her ex's life? Particularly as you are first woman your DP has brought along to social events involving the children they share? This could be heightened if the children like you & talk about you in a positive way.
A positive is that your DP acknowledged the unfriendly response you got from his ex. He did not ignore or dismiss it.
I say go to the next social event but also try to see his ex on a more casual basis......like her partner does with your DP (hope that makes sense). She needs to learn to trust you.

Of course, other posters might also be correct....she has a lovely partner & an ex who is amicable & does DIY for her. You are intervening.

The advantage you have is that your DP recognises that his ex was unfriendly towards you.

Please don't be put off going to the next social event. Show her you are here to stay & your DP is supporting you to have a positive relationship with his (their) children.

.You say you are the first person introduced to the children. I imagine that the kids have gone home and told her you are nice and it's just hit her that there's another woman in her children's lives.

Obviously you've done nothing wrong you can't control how somebody else reacts so don't worry about it.

In an ideal world you'd all get along just fine but the situation surrounding you knowing each other is rarely a recipe for best friends.

I would go even if I didn’t want to as I feel that not going is what she probably wanted, you need to show her that her nastiness had no affect on you, at the next party be polite with her but don’t make that much of an effort, you don’t need her to like you or her approval, she is just your partners ex and you will only need to suffer her occasionally

I know its hard to stare down mean girl behaviour but if you don't go she will have got what she wants. I don't think I could let that happen! I'd want full support of DP though.

I wouldn't stay away from the next event out of principle! You have every right to be there, as you've been invited by your partner. For a woman who's been separated from your partner for 10 years, she's behaving as if she's the one still carrying a torch!! Did your partner instigate the split from his ex?! Insecure people constantly plaster 'loved up' posts all over social media, because they desperately want others to see how 'happy' they are! It could be a case of 'I don't want you, but I don't want anyone else too either' situation, and now she's got to face up to the fact he's not pining after her!! Or she's concerned her 'DIY man' won't be so keen to come to her aide! Regardless of the ins and outs, her behaviour is childish. Go to the event, be very friendly towards her, polite and hold your head up high!

That doesn't mean anything. She's worried he'll stop nipping around to do her odd jobs.

How long are you and your partner together?

I wouldn't give this a second thought. If you're the first partner he's introduced to her or the children in ten years, then it's an unfamiliar, and probably uncomfortable situation. Did she know in advance you were attending?

If you're there for the long haul, you have to go. She's testing you. Don't back off and don't play her silly games. Be polite and pleasant, she'll only show herself up if her behaviour continues.
She's probably worrying that he'll start a second family with you.

Honestly, I've run into people just like that ex. They're all happy showing off their new partner, all over social media so their ex sees it. However, once their ex gets themselves a new partner, the green eyed monster comes out. Because they want the ex to be single and compliant to doing things for them. So if they're suddenly with a partner, they will do things just to triangulate the ex to still do their bidding. They are only happy when the ex is single and miserable. Even though I'm sure your partner wasn't miserable before he met you. That's what the ex thinks.

Keep going and make sure that you do quite a bit of touchy feely with your partner. Also if your dp doesn't tell the ex to wind her neck in the next time she's being a jealous cow. Then you need to talk to him and tell him that she's making you uncomfortable due to her talking about you behind your back. Hopefully dp will say to her to give you a chance and not to be so rude towards you.

However, what she's doing is catty behaviour. Rise above it she is just jealous even though she's meant to be so in love with her new partner. Sometimes people show you who they are. Doesn't mean you have to acknowledge it. In fact counter it with kindness.

100% go.
that's what I do with my ex and I just make sure that I always look fab and am having the best time. just get stuck in, she's def jealous. be your lovely self and tell us all how it goes next time. just ignore anything that's said. you don't need to be friends and she's his ex fir a reason.
sending hugs xxx

Face this woman down and go. Look fabulous. feel confident because she is on the back foot here. If you don’t she will always have the power and you don’t want this.

I would def kill her with kindness. Go up, big smile, hi how are you etc, pay her a compliment.
Best to keep the upper hand in these things!

It is totally possible for her to have moved on happily and be jealous all at the same time. Feelings aren’t rational. For her moving on is fine when she thinks she is the one ex pines for and can’t get over. Seeing him happy enough to have introduced you means she has to get over the breakup and all the small private irrational jealousy possessive insecure feelings all over again.
You should go. Because if you don’t she becomes empowered. Every other adult in the room who knows the situation will see her reaction and know it’s her problem and not yours.

I read this as being you are the first serious partner he has had in 10 years, who has been introduced to his children. This is all new to his ex. I'm not saying it's ok for her friends to be rude, but they will automatically stick with her as friends do!

Give her a message, ask if there is anything you could help with for the next event or if you can meet for a coffee to set some expectations..they will do more than sitting worrying about it

She probably doesn't want him but doesn't want anybody else to have him. Be your most beautiful and charming. You don't have to hide. x

so no actual proof
Just playground assumptions?

Just because you're in a relationship with her ex and he gets on well with her new partner it doesn't mean that she should automatically be best pals with you.
She said hello.
You felt awkward meeting her for the first time; you're the first person your partner has introduced to her maybe she also felt awkward? Maybe she was waiting for you to approach her?
When I first met my partners ex at his parents wedding anniversary party both of us were so anxious we each thought the other didn't like us; because neither of us made much effort beyond pleasantries. In actual fact it was just nerves.
It was much easier the next time we met. But whatever the reason go to the next party, and every party after that - if it is in fact that she was being a bitch then you take pleasure in knowing your presence is really pissing her off!

It’s unpleasant but little girl stuff. Ignore and endure for the sake of your partner and his children.

I would go. She just needs to get used to the idea that he's moving on with his life. Be pleasant so that everyone can see how unreasonable she is if she continues to be frosty towards you.

Go to the party, ignore her for a quiet life and do a bit of dirty dancing with your dp.
She's probably wondering what is so special about you, that it persuaded your dp to introduce you to the dc.
It is a her problem, not a you problem.
I bet she secretly thought dp still loved her and that bubble has burst.

Smile and wave!

Yes, go to the next one, 'nice her' (as I once saw it put) but have something arranged to go on to so you only stay briefly 'just showing our faces, we've booked to see a film / show / band at 9' 😀