My daughter in law is constantly mean, lies regularlly and leaves her 14 yr old and 11 yrold children home alone for 6 days while they were in canada, she does not like my other daughter inlaw, and always seems to need to be the center of attention, for 15 yrs now I have been more than nice, but I can no longer do this, she has told my son many things that are not true about this entire family, but she has made me feel like I am a bad person what can I do

I have had instinces in my life where, I have been made to feel like I am a bad person, mostly from a certain daughter inlaw and from my own brothers. Help me know how to deal with this it is depressing me

How do they say you are "bad"?

grandmar, people don't make you do or feel anything unless they have you hostage and a gun to your head.
You have allowed yourself to have these feelings, and we don't have a clue about even one little reason for it.
So either tell us what's wrong, or ask them to sit down with you and talk it all out.

As Eleanor Roosevelt said-"No one can make you feel inferior without your consent".

How are these family members saying/making you feel like a bad person? Maybe it's something you have done that you haven't forgiven yourself for yet (that is only a suggestion), or maybe they are just gossips.

Either way, you need to find the strength within to KNOW you're a good person and you do the best you know how. Tell these people who are supposed to love and support you that you don't appreciate nor accept their behavior, and how can you help them understand you better? Communicate to them how they make you feel, but also be prepared to listen to their interpretation of things as well. An open and calm dialogue may be just what you all need to sort out any misunderstandings and heal any damage.

Do you have any reservations about telling her to her face just how you feel? It is perfectly legal to leave l4 year old at home and in charge of an 11 year old.
Your description sounds just like many other in laws I have come in contact with over the years.

Just tell her up front exactly how you feel.

Great E. Roosevelt quote; I love that and so true!

OK, you came back and changed your original post a little to tell a bit of the story.
She can't 'make you' feel like a bad person. You don't get along with her and feel awful, but you are the one turning yourself into a victim.
It sounds like you don't stay out of her business either. What she and your son do with their children, short of beating them or using drugs, is none of your concern.
So if you dish it out, you have to be able to take it.
Stay away from her or accept that your son married her. One or the other.