Saudi affair

Good day! I would like to ask for your advice.This is with regards to my husband who is an OFW in Saudi Arabia for 7years now. We are married in civil rights.I learned recently this month from his co-worker that he converted to islam 2-3 months. Ive learned last 2011 that he had a girl friend or worst an affair to a Filipina nurse working in Armed Forces Hospital Southern Region in Khamis,Mushayt,Jizan,KSA. I had a talk to one of the girl's co-worker that my husband and the girl is now living in one roof somewhere in Abha since last year 2012. My husband went on vacation here in the Philippines last Sept.2012. I confronted him about their affair but I knew he lied to me. We have 4kids - 3 are already in school. I know that my husband is very responsible when it comes to his financial obligations to us. Just recently, he threatened me that he will cut-off his monthly obligations to us.I don't want to force him since it's his obligation to us and I don't want that monetary obligations would be our source of conflict. Let's say, if proven, that my husband and his gf in Saudi together converted to Islam and got married in islamic rights 3 months ago, will their marriage in islam or in Saudi be honored/legal here in the Philippines? What if the girl is really 2-3months pregnant? Her co-workers told me that they hurriedly converted to islam and got married because in Saudi if the the girl or any woman got pregnant from a man who is not his legal spouse will be punished and deported.

My question is; is their marriage valid in the Philippines since they are Muslims? Our marriage is not anulled yet. Another question that I have is that; does he has any liabilities in the civil law?

Please enlighten me.