Gosh, are you always this defensive? is that how you counter an argument usually?
I haven't read that you SAID you dislike her, its just that you have failed to say a nice word about her, which is really sad.
She is four, she wont understand that it is a difficult situation - because she is four. It sounds like her mother hadn't got over the split for whatever reason as she was crying to your DP about you being pregnant - there must have still been feeings for him. You have to put yourself in her shoes, you are being painted as the wicked step mother by her mother - she sees you as someone who has taken her daddy away, you are a threat to her. This is partly because of her mother and partly because you get to be with her daddy all the time, just as the new baby does. I guess it goes with the territory and I am the first to admit i could never be a step parent. I couldnt be a step parent becaue i couldnt love someone elses child no matter how hard i tried so i wouldn't do it as it wouldnt be fair on the child.
I am sorry if my post sounded harsh but you do really slag this little girl off (and her mother, who at some point your DP loved enough to make a child with, maybe you are still insecure about this - i would be).
Yes this is a support forum, but support doesn't mean always agree with the OP. Did you want people to come on here and say, oh yes, you poor thing, she sounds horrible and her fat mother sounds like a cunt as well. Good luck with the healthy eating, we eat healthily too, however it is difficult when your child goes from happily eating all the quinoa and cous cous you dish up to pushing away anything that isn't fish fingers and pasta. Don't let food become yet another battle ground, let her have what she wants for dinner - a fish finger never killed anyone yet, then introduce other healthy things as treats - if she doesn't have this at home then it will be treated as a novelty. If you force it on her, she will just rail against it.
All the adults in this little girls life need to walk a mile in her shoes for a little while because she doesn't know which way is up just now - it must be a big upheval for her to have a step-brother or sister come along who daddy lives with all the time, especially if her mother is being shitty about it.
But do feel free to tell me to shut up if you don't like what i have to say, as an open forum i will exercise my right to express my opinion, you don't have to read it