You were not clear as to whether you were able to get the first separated-neck out of the chamber.

You may have two case-necks stuck in your chamber, one inside the other.

I do not know your level of gun-tinkering skills or the tools that you have.

There is an old tool, a "Broken-Shell Extractor", that is used to remove a separated case. There are other various tricks that work.

DO NO HARM! Do not try prying it out with a screwdriver. Inept attempts will scratch or gouge the chamber!

You just might want to take it to a competent gunsmith.

"Psteinmayer" identified the cause of the problem. Your Brass is old and has become brittle from 'age'.