emmak8383 do you know where you got the idea from that feeding a baby in the night will "ruin her"?
Our society is really weird about BFing, it's peculiar to certain cultures sucj as ours, but it's not like this the world over.
Nature has designed boobs for feeding babies. Babies need feeding, and most of them will need feeding at the night at 4 months. Your baby knows this, she knows she's hungry. Your instinct knows you should feed her.
However you've received the message from somewhere that there's something wrong with this, which is not surprising as this message is everywhere in the UK!
But it might be worth reflecting, do you know where it came from? A book? The older generation? Friends? Wider society & the media? Wherever it is from, they're feeding you misinformation.
You absolutely can't "ruin" a 4 month old by comforting her, or feeding her.
Trust your instincts, you know what to do :)