READ FULL STORY (SO SAD) What my wife to be did to me.

Dear Sir/Ma,
I love the way you treat people’s issues in The Guardian newspaper. I am well convinced that equally, you would give a better advice on my own issue.
I am a 31-year-old engineer, currently dating a 26-year-old lady. Our relationship has lasted up to four years and our families know about our relationship.
On January 1, this year, I went to my lover’s house and informed her family about my intention to marry their daughter by December this year, which everyone was happy about and some arrangements about it have started going on. But since March, my heart started troubling me about my lover. I became extremely worried for an unknown reason. I could not figure out what actually made me to worry about a woman I have been with for four years plus.
Due to the nature of my work, I travel out of the town for projects. Sometimes we stayed up to four months apart, but I never for one day suspected my wife before this time.
I began to feel suspicion within my heart and started doubting her. I even complained to her that my heart was troubling me about her and probably something was wrong somewhere.
Though from the initial time we started dating, I warned her that dating another man apart from me would have a serious consequence on our relationship and that she is free to inform me and leave whenever she does not want me anymore.
The restiveness of my heart became too much, so I went to see my grandfather and informed him about my sudden change of feelings towards a woman I so much loved and trusted before.
My grandfathers told me that it may not be anything to worry about and that I should call the girl and ask her whether she has been cheating on me.
So, I invited the girl and told her that she must tell me the truth, whether she has been cheating on me since we met. I told her that failure to tell me the truth would be the end of our relationship that day and that I am aware she has been cheating on me, but if she still denies it again that day, I will end our relationship.
I also promised her that whatever truth she will say, I will forgive her, provided she promises not to do it again.
She was denying, but after noticing that I was serious to end the relationship that day, she started crying and was asking me if she opens up whether I will still forgive her and go ahead to marry her, and I said yes.
I got the shock of my life when she told me that she has slept with 12 different men on many times within the said four years we know each other.
I became devastated and fell sick. After some weeks, I recovered and vowed not to do anything with her again. I have informed her that our proposed marriage in December would no longer hold and that she is now free to choose any man she wishes for marriage.
Now, our families are calling me names and begging me not to disgrace them by canceling the marriage with the girl, which many people have started hearing about. And the girl is threatening to kill me and kill herself if I leave her to marry another woman.
The advice I want from you is how to deal with my family and her own family to understand my feelings.
As for the girl, I have forgiven her, but will never marry her. I can never keep a promiscuous woman in my house as wife. I can never trust her again, because she is capable of sleeping with my driver and neighbours.
Regards.