There are a few ways to get out stuck BB cups ... many will also take the threads. I think there was something I found on Sheldon Brown's page involving a 1/2 in threaded shaft, multiple nuts, a crescent wrench, a ratchet, and a breaker bar. i will check.

https://www.sheldonbrown.com/bbcups.html
https://arcady.genkin.ca/2016/03/an-...-removal-tool/

The idea is that as you turn the ratchet, it tightens the bolts and washers onto the right-hand (fixed) cup and increases your grip the harder our turn. Sometimes the cups get galvanically welded in place and the little flats on the cup don't offer enough purchase.

Lots of penetrating oil, lots of patience.