His poor wife:
-Invited a complete stranger from another country into her home.
-Has given up sexual intimacy with her husband because it upset you.
-Has given up having a partner to share a bed with because it upset you.
-Is basically raising small children by herself (with a couple of other adults in the house who don't really get involved because they don't really like kids).
-Is trying to maintain some kind of normal family life by insisting on dinner together (which is healthy for the kids).
Tell me again how you're getting the short end of the stick? I suggest that you get your own house and see where the chips really fall. If he says that if it comes down to it he'll marry you, what do you have to lose? You're obviously not happy in the place you are in your life. So change something! The only person who you control is you. Make choices that are good for you, not choices that are motivated by trying to manipulate someone else into making the decision you want them to.
Everything will be ok in the end. If it's not ok it's not the end.