Should I fight my sister over my inheritance, if she is over the will and refuses to honor my mother.

You need to contact an estate litigator (I am not one, although I know a number of them) as soon as possible, before you run out of time to answer. Based on your question, it sounds like your sister may be appointed as the Executor, but she may not be a good choice for that role. If the petition you received notice of would admit the Will to probate and make her appointment as Executor final, then you may want to challenge her appointment and propose someone else (possibly yourself) as Executor instead. I can't tell from your question exactly what you've been served with, but my guess is that it's probably a petition to probate the Will and get your sister appointed. If you don't answer in the required time, and that is what it is, you will lose your chance to object to the probate and your sister's appointment. If she's really not a good choice for that role, you could end up with her damaging the estate and your interests in it, and then having to try to have her removed. It would be better to get that aired out up front. But it should not be a do-it-yourself project. Get a consultation with a good estate litigator and see if they think you have a case worth pursuing. But don't wait; you will lose your chance very quickly. Best wishes to you.