What should I do in this situation I am in?

Long and short of it, I fell in love with a girl that was engaged, she told me she loved me and was confused, but needed time to break it off with her fiance, I let her go, she stayed with him for a little while longer, then broke it off with him, she didnt tell me her family did! A week goes by, and I see her out with someone else, and she acts like she doesn't even know me then leaves with him!!!!!!!! She left her car, so I KNOW she went to his house!!!!!I am so "p"oed the last words she said to me 4 months ago were" I love you! "I feel like we were meant to be together!!!!!!!!!!, but I need time, I never heard from her after that, on top of it all we were best friends for 2 years before that!!!!!!! " What kind of woman does this to someone, my fiance died in a motorcycle accident 16 years ago along with my best friend(they just took my bike out for a spin, I loved them both so much!!!!!!!!), and she knows it, I never thought I would love anyone again,then I met her, what kind of person does this too someone else!!!!!!!!!!!!!! I am so devasted I am turning online, how sad is that???, it is late and my father is sleeping, I would call my mother, but I lost her to cancer 10 years ago, I am best friends with this woman's brother, wife and kids, her mother even loves me! I am a successful man with many friends who would do anything for me, and who hate her for what she has done to me, how do I forget and forgive a person like her, and how do I keep the peace with her family, who is VERY. VERY, important too me, especially her older brother who is more like family to me than anything????????

The thing is, is the fact that she told you that she loved you while she was with her fiance, she then broke up with her fiance to be with another guy. There is a problem with all of this. She is not faithful. I don't mean to be rude but you don't want a girl like that because if she will leave her fiance for another guy and also tell another guy that she loves them in all honesty she doesn't know what love is.

I'm sorry to hear of all the pain your going through and have gone through but there is a woman out there that will treat you right and love you the way you should be loved but she is not the one.