I don't know if this is the only thing you can do, but I had the same thing happen. I put the stem in water and each day clipped the end of the stem off about 1/8 in. Most of the blooms still opened, but the stem only lasted about a week. It was better than nothing. I left the rest of the stem intact on the plant and continued caring for it as usual. After about a month, another shoot started growing from the stem spike. It only had 4 blooms, but again, it was better than nothing. Hope you have the same luck.