NTA, everyone shares answers once in a while in school but not if its something that could get them caught. and usually youd do it to help someone understand certain questions. id often get stuck on questions and my friends would be kind enough to help me through them.
offering to help her through the questions is alot kinder than sharing the project cos at the end of the day it will benefit her much more. missing homework may feel like the end of the world but looking back if youre really stuck and you have a decent teacher she should go to them for help.
but yeah doing this could mean neither of you gets a grade which wouldnt help her either so youre doing both of you a favour by not giving them to her