I want Legal Separation from my infidel husband

My husband and I were married for 12 years. My husband is working in Dubai as an Aircraft Engineer an I lived with him there for 10 years and then decided to bring my children here in the Philippines last December 2009. All our 4 children were born in Dubai. On May 2010, I was told by my friends that they saw my husband holding a woman on the mall there. I confronted my husband about it and of course he denied. Then when my husband gave his old phone to my daughter, I found a girls number there and my instinct told me that that must be his woman's number. I called the woman and threatened her that if she would continue seducing my husband, I will report them to the police in Dubai. Then the woman told me that she would be resigning and will leave Dubai. I did not believed her. I know the likes of her in Dubai. They cling to a man like leach just to have someone to support them. This woman has been separated from her husband and have 2 kids. I cannot file any complaint against them as I was not holding a proof on their illicit affair until last week, I was able to open mt husband's Facebook account and found their exchange of endearments and stating they're living together. Can I use those conversations on FB as a proof?