It's so hard to be the bigger person in this situation but ultimately the rewards are yours. I thought it might be helpful to give the child's perspective here.
I was a kid of divorced parents and lived with each of them for a number of years. In the few years I was with Mum, she never badmouthed Dad - even though he was the 'leaver' and wrecked her health and security. She always kept her gentleness and sense of humour, and tried her best to make things fun for me.
Dad badmouthed Mum though. Even though he earned ten times more than her and lived in big modern house, he was always complaining to me and my brother about the (average) child maintenance he paid her, the (tiny amounts of) money she took from their joint account as a SAHM... etc. He married his latest OW and they had two babies. He divorced her a year or two after I fetched up.
From the age of 6 I recognised the absolute injustice of all of this and I was always wholeheartedly on Mum's side, though I had to be careful not to say so to him.
If Mum had badmouthed Dad too, I wouldn't have known where to turn. I'd have been in no-mans-land, caught in the crossfire between two angry adults who put their own feelings before mine.
So while it comes from a good motive, I think the argument for sharing your upset, rage and disdain for their Dad with your kids - in the spirit of empowering and not gaslighting them - is misplaced. Of course that doesn't mean going to the other extreme and smiling through the pain like some Stepford Wife. And tbh, in my case, a tiny bit more reality from Mum might have helped.
But that's the tricky course that all parents have to navigate with their DC. And on the whole I'd say that tempering your emotions and modelling a sense of humour and proportion, while acknowledging life's inevitable shit, seems to be a good basis for your own and DC's emotional health.
Sure, I liked that dad could buy me a bike. And I loved the school I went to in the nice suburb where he lived. Same as your DDs will enjoy being flower girls. But apart from that, living with him was unpredictable, scary and grim. Your situation isn't exactly the same of course OP, I'm sure your exH isn't in the same category as my Dad! But what I'm saying is, behaviour will out. Your exH cannot help but reveal his true colours to your girls. And even if they don't talk about it, they'll never forget who makes them feel loved, secure and prioritised, who's always there for them, whose home is more relaxed...
You asked how you get over it OP. The first and biggest step is to admit to yourself that the man you loved turned out to be a Grade A shit. Not your fault, it happens to the most discerning of us(!). It's just life. And once you stop grieving the ghost of the lovely man you married, your life will feel right again.