Ali, I think you have to accept that xb/f does probably feel something for Helen and it may not all be guilt induced. It may not be the same feelings as he had for you, it is quite likely to be different.
I guess he wouldn't be the man you love so much if he just discarded her without some sort of feelings or guilt towards her and you. So I guess it will take as long as it takes for him to break it off, working together not withstanding. Someone else pointed out that he really then needs sometime on his own without being in a relationship so maybe friends is all you can be for awhile, after all you really neeed to know that if and when he returns to you that this time it will be for good and he wont run at the first sign of trouble.
Unless his friends have some kind of crystal ball, I would settle in for the long haul, after all you only want to go through this madness once in your life! Don't we all.
