Hi Van, and Mrs. Van.
There is obviously a lot of longing and anxiety here. I don't know you, but I am really sorry that any of you are experiencing these types of feelings. It seems like love should bring warmth and happiness. Instead sometimes it brings feelings of fear and painful longing.
That being said, I guess at a time like this when your head is buzzing and you can't believe you all have to just be in this holding pattern, it's important to start from the things that are kind of immovable. For one, since your friends have company it is up to the other lady to find any time to really communicate with you. If she doesn't, there's not much you can do about it. Another thing is that whatever rules her husband lays down, you have to respect not only the letter of, but the meaning of, i.e. between the lines. The "no unsupervised visits" thing says loudly and clearly to me that he is afraid of what would happen if you were alone with his wife. Sexually or emotionally or both, he feels threatened enough that he has to be there whenever you're with her. This is not a good sign. Maybe he'll get over it, but if he doesn't then he is basically saying "she's mine and you're not going to have any part of her".
Also, Mrs. Van is struggling with this. This means that first and foremost, you have to do whatever you need to do to reassure her she is not losing you, that you are committed to her emotionally, even if not exclusively. But she has to know that she can still count on you for all the things she has in the past. That whatever you feel for someone else, it doesn't interfere with the love and devotion you feel for her. This is tough for most people to figure out and to believe.
You've had a while to get your head around the idea of loving more than one, and how that can enrich everyone's life as opposed to taking away from it. I can't really help with this, as these are ideas I was imbued with as a teenager by reading a bunch of books by Robert A. Heinlein (Time Enough for Love, Stranger in a Strange Land, Number of the Beast and more). It has always seemed natural for me. The key is that all the primaries know they are still primary, that 20, 30, 40 years from now, their love will still love them regardless of this other relationship. You'll still take care of her when she gets sick. You'll still hold her when life deals her a blow. You'll still BE there. This mindset is so hard for people to get. And truthfully, not everyone is built that way. If they come around, it will take time.
I really hope that your relationships all navigate these waters. It is quite possible, with lots of nurturing, but only if everyone is accepting of what is happening and wants happiness for all, in whatever form that happens. I also hope that you and the other three all get to air your feelings with honest and positive-attitude discussions.
Finally, I know it's hard to wait. That's really tough to handle when all you want to do is deal with this important thing in your life. The only thing I can say is to try to think about how things might be six months from now, and how to best deliberately get there. Letting something happen too quickly would probably not help.
I hope you keep coming back and posting.