I have been cheated on, what should i do? it hurts so bad?

My Girl Cheated on me Sat. (i did not find out untill the up comming Wed.) for the Mon-weds untill i found out she was all over me like nothing had happen. I had asked her what she did over the weekend and she said went to a party with her "mom" (yeah... ok?) and i was joking around with her about her getting "Some" wit out me... she started laughing and never answered. then i heard a rummor that she had wanted to buy a PREGNETCY test... i asked her about it and she said Yeah.... for my sister.... so i was like ok w/e..... the next day (wed.) my good good friend told me that She had texed his gurl telling her that she had had on sat. And the friend was like "ok Was it Good with "my name" and she wrote back sayign No it was with another guy.... so i asked her later on that day if she had any thign to tell me and she said NO..... si i finaly told her i KNEW about it and shes a lier and its over. NOW she is CRYING her *** off saying how sorry she is ..... Should i take her back?