Should I forgive her? Or would that just make her take me for granted again?

She would betray you and you would be hurt over and over again . You will make new friends and find new one's that will like you for you . You have given her more then enough time to be a good friend and you have said she keeps betraying you . I have answered your other posts about this as well and realize this is something that is bothering you very much . I know sometimes it seems it would be just easier to forgive but in the end it will really just end in you being hurt over and over again as you have in the past . She is never going to change and the quicker you realize the quicker you will be able to move on with your life .

if it is really happened 50 times , i strongly advise u to leave her , i know it can be difficult for u , but u have to do this , coz i am sure it will happend again ,, so dont forgive her this time and finish it ,,, good luck

The best advice I could give you is to say your prayers and follow your heart.