Im so sorry that you are dealing with this, it is in man ways one of the most painful things a person can go through. You are being betrayed by the person you love, the person that is supposed to love and cherish you through thick and through thin. You will find lots of support here on this forum, as well as lots of advice. Some of it will be blunt and painful, some of it may be of little value to you, but if you really take the time to listen, you may just find the support you need to get your relationship to a healthy place once again.
Just so you are 100% clear, backpages is a web site where people sell sex. Your husband is going to have sex with a prostitute while he travels for his business trip. There are several things you need to do in order to know how to proceed. First and foremost, you must ask yourself if you still love this man, and if he is worthy of the effort it is going to take to fix things. If the answer is no, please go consult with a divorce attorney while your disloyal husband is on his business trip. Find out what your rights and responsibilities are when it comes to divorce. If the answer is yes, then read on.
Since he has already demonstrated that he will deny the truth when confronted, you will need rock solid evidence that he can't deny. While he is gone, you will need to install a good monitoring/keylogger program on all of the computers in the house. You should also install mobile spy (www.mobile-spy.com
) on his cell. Gather your proof, save copies and store them in a safe location, then confront him.
Tell him you expect him to be 100% honest and transparent with you if he wants to stay married. That means you get total access to everything, all his passwords and accounts. Cell, bank, facebook, whatever else. He can no longer delete anything without you reviewing it. He must also start attending individual counseling to figure out why he has so little respect for you and the marriage, and once he has a few sessions under his belt, he mus attend couples counseling with you to learn how to have healthy boundaries and how to hep you heal.
Read through a few threads in this section for some other ideas of how to proceed. Look for one called "cwi noobies start here" I think that's what its called, im sure someone will post the link soon.
Good luck, keep us posted.