"It was acting!
The competition for worst is ferocious, but for sheer stupidity Sebastian Shaw in X-Men First Class has got to be considered. Killing a kid's mother is the foundation for a partnership in conquering the world?
His killing Magneto's mother has nothing to do with his founding of the Hellfire Club. They're separate events.
His superpowers disappear so that he can be killed by a slow moving coin?.
They didn't "disappear". Prof X was keeping him from using them.