Cat eating cardboard boxes

So my cat started eating my cardboard boxes 2 weeks ago and I don't know what to do and how to get her to stop.
I love on her, play with her and everything but I don't know if maybe she is bored and doing it or if there is a serious problem with her.
My cat was abused when I first got her; my vet questioned my husband and I about abusing her(broken ribs, she's been hit in the head, she's been bit) I'm afraid to take her to the vet because I'm afraid they'll tell me to put her down. I looke online which is probably something I shouldn't have done because it made me more scared it said something about my cat could have pica. If you have any thoughts please let me know Yes she is sleeping in a box but she wants to sleep in it and I took the box away when she started eating it

How old is your kitty? 

Does she actually eat the box or does she bite and tear it?

She's probably just shredding it up for fun. Mine do it too, the cardboard has an interesting texture to them.

If she is actually swallowing it it's worth talking to a vet.