Should i stay with this girl?

okay. ive been going out with this girl for little over a month. i thought it was great. but she had broken up with her bf just a month ago. i wanted to wait a month. so i did and now we are going out. im not one to argue with my gfs, like ever if they argue i just say there right w.e i dont like to argue. now we had a argument. and instead of talking to her friends about what we said, she went to her ex and talked **** about me. that was strike one. strike two was she lied to me and said she was hanging out with a friend, when she really went for a walk with her EX. strike three just happened. she said she got ride of all the pictures of her and her ex. now i know she had alot of them, but when i was looking at her pictures, she had pics of her and him. they werent kissing, they just had pictures. the thing that pissed me off was it said the 6/13/12 on the picture. that was yesterday. im like wtf?!?!?!? all of my friends say shes not worth it. break up with her, even my best girl-friends said to break up with her. BUT heres the thing. i really like her family like there so nice nd ****. idk what it is but i stay with her. now her mother died in december like a day before christmas happened. nd her bday is on sunday. idk if i should break up with her, but i dont want her to be alone. i just dont know. please someone help. maybe she feels like she needs to be with her ex cause he was there when her mom died, i just idk.