Homealonealways I feel so sorry for you and can't begin to imagine how you are feeling, but what other posters have eluded to sparked a memory for me and thought I would pass it on as someone who was actually there to witness the male FIFO lifestyle. Sorry, this will be long-winded as I don't have time right now to edit to a shorter message which might omit some relevant info.
Firstly, I am not saying your H is involved in this but I feel it's something every FIFO wife should consider. A few years ago I was holidaying in a country where FIFO work was prevalent and a staff member at the hotel where I was staying directed me to the local exPats bar where I could mix with people who spoke English...not being racist, but I found it difficult being understood in the native language of that country.
The first time at this bar, they came across as being friendly and we had some good laughs etc with never a hint of anything that was not right (in relation to their family back home). Usually I'm not a club/pub type person but in a strange country you don't really know where to go and I was invited back the next night for a Trivial Pursuit-type night, which was great and a lot of fun.
Once the contest part of the night finished, it was like a door was opened and their morals went down the tube, big time! I was propositioned many, many times including group sex, by just about every UK exPat there, even their manager/boss who had a really foul mouth and some of his suggestions made me not only blush but fearful if I was to refuse, more on this further down.
I think just about every man there had an Asian family...wife plus several biological kids...this was openly discussed with lots of chest-beating as to how many 'extra' kids they had over and above their kids and DW back home. I was totally gobsmacked as while I knew this could easily happen, what I didn't expect was the open discussion about it and the fact that every worker was the same. I am sure my jaw was on the floor the whole night because I believe in true monogamy, always have and always will, and NO WAY was I going to be the OW.
Some of them even invited me to fly back there each 4-6 weeks (or whatever the timeframe was, can't remember exactly now) and they would pay my air ticket and accommodation (split between all of them) as they wanted someone other than their Asian women....don't wish to write the exact words they used, but I'm sure everyone who has replied here will get my drift. They are words I never use in private, let alone post in a forum, but essentially I would have been a FIFO sex worker for this select group of exPats. NOT my style at all and definitely NOT the reason I was in the country in the first place. I was there on the last leg of an overseas trip with a friend, who had to return to work sooner than I did, so I decided I would spend the extra days there having a look around and doing touristy stuff.
It was extremely difficult to get away from them that night, I'm sure you know what men are like when there's a group, they egg each other on. At first I tried to escape under the guise of going to the loo, but one of them noticed me slipping out the door and attempted to follow me to my hotel. Fortunately (for me) I was flying out the next morning and while I am normally against lying, this time was an exception and I gave a different hotel and that my flight home was another 24 hrs away and with a different airline, to cover my tracks.
My reason being, that I knew they would be extremely hung over the next morning judging by the amount they were drinking and my flight was quite early so I could slip away before they woke, also I was drinking CocaCola as I suffered chronic migraines and alcohol would wipe me out. I returned to my hotel in the wee hours of the morning to collect my luggage and went to the airport and sat in a corner of the departure lounge (where I couldn't be seen) in case someone followed me there. I truly feared for my safety as these men turned into animals once they had a few drinks and self-preservation was foremost in my mind, which is why I was giving incorrect info about my departure etc.
Some of them even wanted my home address and invited themselves to visit in my home country, but this too, led to a fictitious address.
As above, I truly hope this is not the situation with your H, but it might help someone now or in the future. I wish you all the best and, like me above, think of your self because nobody else cares what happens to you. Sorry have to rush off now.
Good luck 