if someone your love is pregnant with other man's baby?

How do you felt if your girlfriend or wife is pregnant other man's baby? of course you will be sad, anger and other mixing feeling. If this happened, just try to forget about her, try talk to your parent, ask for same advice. I tell you, i use experience this kind situation. i know how felt something like revenge-worst by creating killing plan. just let it goo... let it gooo...(frozen) - sorry  Bad English