Oh ksfrye, I am SO sorry. The only thing worse than bad news is more bad news. Its a terrible day, and I hope you can have a good cry. You deserve that (and OH so much more!) The bruised soul, the bruised savings, the bruised body... its just awful. I hope that your doctor has some ideas for you at you WTF next Thursday.
Its great that you have a frostie there. 50% sounds very cautious on his part. I think that the thaw rate is a good bit higher, but I am not so studied on that. I've never had one.
With such perfect blasts, it still does happen that they are not sound enough to survive. Doctors only know what they can see for the 5 days they have the embryos. Perhaps he will order some karotype testing before FET. I am curious to know what he has to say.
Sending you lots of strength, and I hope you and your husband can find a way to heal and move ahead. Hugs.