I had a bestfriend for 15 years and like 2 1/2 years ago her ex boyfriend n lil brother came to my house put a?

Gun to my head n robbed me. Keep in mind i was pregnant and my son was in the other room. She had left an hour prior to this happening and she called me 15 min before they arrived. And the main thing that points all fingers to her is that she gave them the keys to walk in my home. Now years go by and im still confused about why she did that to me? I really want to know why then she lied to me and on me to any and everybody. We never had a argument fight or anything.. I just dont understand. People said she was jealous of me but i cant see why because i let her move in with me rent free no bills to pay she ate wht i had and anything i got i shared my last with her. But when i wake up this morning to check my facebook i see that she wants to be my friend?? Um....im thinking to myself again???why why why im confused what is it you want from me now? Im not rich i dont have anything....so can u tell me what to do and what do u think is up with her...