I feel for you. I've lost a crank or two that way, even after stopping and using lots of penetrant after the pulling got hard. Sometimes the crank threads lose the battle - even sadder when it's a rare and valuable old crank you wanted to save.

I've tried a jaw puller, but with 0% success. What has worked is multiple cuts with an angle grinder, working carefully in case you want to salvage the bottom bracket.