Re: What's going on?
You are certainly not crazy for wanting to know everything. That's how most other betrayed spouses feel. But I don't think you'll be able to get anything out of his friends. Another polygraph might give you more closure. If he balks at it, then it's time for divorce. In fact, if he balks at anything you ask for, it's time for divorce, now that he's revealed himself to be a three-time liar (I'm starting to lose count).
A lot of men don't care about a woman's face. All they see is a nice body on a woman who is very willing and sexual in a way that their wife might not be. But they don't see these women as anything but throwaway sex toys. And the women like this in SE Asia are often working multiple men at the same time, asking for gifts of money, professing their "love", lying about their own faithfulness, etc.
Once you know everything--and I think you are approaching that point--you can begin to heal. But this will be a long process. If his transgressions stayed within limits that you can come to terms with, and if he shows sufficient remorse, I think you will get past this in a couple years. You can have a healthy marriage again. It's been done before. But you will never fully trust him again, and he should be made to understand this up front.