No I hadn't refused to help either of my daughters at all.
So why, at that point, didn't your daughter say "My mum has helped me with everything thanks, what makes you think she hasn't?" There's absolutely no way I'd allow someone to talk about my mother like that. I certainly wouldn't be associating with them afterwards.
Family always seem to take my sister's side because she lies to them. She's nasty to people and when she's called out on her behaviour she cries and says she's being picked on.
This is my point - She has a reputation as a liar, she's nasty to people, she throws tantrums and cuts people in the family off...so why, knowing all that, are members of your family still so willing to take her side over yours? It's not really painting you in a good light, unless you're suggesting that your entire family are unwilling or incapable of separating truth from fiction?
Your question was whether you should distance yourself from your sister and I think you absolutely should. But I'd be willing to bet that you have some issues of your own to work on, and if you don't, it might not just be your sister you end up distanced from.