Oof, starting a relationship and marriage where you can't take someone's name, and have to buy your own ring - probably not promising signs for the longevity of the relationship.
Probably you can supply more details, but initially my suggestion is to focus on your D7. Kids are the ones who get hurt in divorces, and have the most long-lasting effects. It's "easy" to go get a new boyfriend - not as easy to go get a new dad, or figure out what your relationship is with a stepdad and so on. She needs to be assured of her innocence in this, and she should be your highest priority.
If you want to do ANYTHING to save your marriage, run it through the D7 filter first: is this best for her? Am I putting her first no matter how I feel about H? And so on.
Secondly, I would then protect yourself, and it sounds like you're handling that with the orders you've filed, and so on.
His age is certainly right for a MLC (mid-life crisis). Also, I'm sure the traveling you've had to do has impacted your relationship.
Can you supply more details of the last few months? I'm curious if there are marital problems, or you were just gone alot, and he found someone that would talk to him?