I posted this earlier from another computer now it's gone...spooky...

I cropped a stretch lace top after removing the ugly lining. The neckline was really high so I cut it down, too. In order to not have a raw cut at the neck, I attached small width bias tape. The tape totally stretched out the neck so it gapes when I have it on and move. What did I do wrong? What would be a better way of finishing the neck to have a pretty edge but retain the stretch?

Thanks much.