I just deleted /home/purism/.purple/chatty/db/matrix.db and /home/purism/.purple/prefs.xml that made chatty responsive. Opened preferences disabled and deleted matrix account.
I would like to re-add matrix account so I may try again now that I know how to work with it if it freezes again
[EDIT]: turns out I can sign-out from other (main) device and then chatty will allow opening preferences.
However it’s still not usable with matrix, I’ll wait few updates or try to dump debug messages