Troublesome children...opinions please.

I have met a fabulous partner. We are compatible in so many ways: morals, interests, wishes for the future, outlook on the world, feelings for eachother appear mutual.
From one last relationship with a very difficult step daughter...I have been very anxious about a new relationship.
I generally get along with most people, I can chat with most and fond something in common.
I had slight alarm bells due to huge differences in how we both function. I have two children and always have had to work full time. I'm often tired and haven't had a holdiay since 2006.
His daughter on the other hand is looked after by a very wealthy farming family plus husband, 4 kids under 12...yet in three months has managed 4 trips abroad and one in this country without children she is an utter princess and I am very careful not to tread on her toes when it comes to her relationship with her dad.
They are very close and she Is definitely used to everyone running around after her (despite my partner maintaining his daughter is the picture of an Independent woman)
So, slightly green eyes monster aside...I accept we are different but hoped to be able to gently become accepted into the family.i don't want things to change for her and her relationship with her dad and I am adamant about impeding on their time...however, did spend some time with her yesterday.
It wad an utter nightmare. She talked about herself and the kids the whole time,little snipes at me etc which I politely ignored. We attended a village "do" and although I was there with her and her children, whenever she stopped to talk to friends she didn't once Introuduce me.
She is a very bright, chatty, eloquent young woman with impeccable manners...she knew exactly what she was doing.
I let it go....aware that my last relationship was very difficult and not wanting to bring those feelings into this relationship .
However, over dinner, I met her husband and some family who chatted about themselves the whole time( they do TV stuff and are quite high brow...everything is designer etc etc....I could tell they looked down on me) I showed good manners and chatted a little, nodded asked questions etc but there was a definite atmosphere especially about the dessert I brought. It didn't seem to go down well with her that everyone else liked it. She had to keep bringing the chat back to her. It was thoroughly exhausting.
The thing is, my last relationship broke my heart entirely. I am probably still not over the nastiness of my exes children and the thought of it happening again is awful.
..and it is!! They are clearly threatened but also used to having everything their own way. It's the Waltons, meets Buddy the Elf meets The Great Gatsby and I'm more like
A mix between a David Attenborough out take and Mr (Mrs) Messy from the mistermen books with a bit of the Borrowers thrown in.
Very different.
I got really tearful when I got home and I just wanted to be left alone. The feeling of not fitting in and being so rudely treated while everyone else seemed oblivious really hurt.
Even her husband jumped in and disagreed very strongly about something fairly gentle I commented on and wouldn't let it go. He repeated himself until everyone just agreed. My partner thinks I'm over tired and over emotional I think...but this doesn't bode well to me at all.
I appreciate family dynamics are difficult but I don't want to waste any more of my life with the wrong man.
If he isn't prepared to notice what was going on...(even if there was no action...I hate arguments etc but ay least to be seen and heard as very important to me)
Any thoughts please?
I am obviously very careful and have suggested he goes to see them today without me and that most visits can be without me if it causes issues
I work full time anyway and don't have the excess energy....