My female Cookie just had her first litter of puppies this morning, She had one little girl puppy. Well mom and puppy are doing great. But she WILL NOT feed the baby on her own

She stays with me at ALL times and
will notfeed her puppy unless I put her in the box and sit there beside her, well I didn't mind doing that and I just figured it was because this was her first puppy, but I was sitting there waiting for the baby to finish eating and it stopped eating and crawled up between her 2 front legs and all of a sudden she jumped up and attacked the puppy

I stuck my hand down there and she stopped but I thought she was going to kill it, she starts looking at it like it is a mouse or something she wants to kill and the she goes for it (but she doesn't hurt it if it stays down near her teats, she only bites her if she craws near her chest or head) She will stay with me and if I go in the room where the puppy is being kept she will sit there and watch it but won't get in the box with it

Do any experienced breeders know why she is doing this?
I guess I will just lose a few weeks of sleep. I will be sitting up and watching the feedings as I don't want her to harm the puppy