I know everyone say that mulberry are though....well they are though with me alright...
I never manage to keep one alive till now and the sudden death generally happens when I disturb there roots for some reason.
Last year I potted an old one, even bigger that yours, and it started to bud like crazy.
Then I accidentally flipped the pot with the garden hose while I was watering. I realized it immediately, put back the pot vertical and replaced the soil properly but it had already started dying and never stopped...
Now I have the log to put a tanuki on it...
Good luck with yours and if, by mistake, I end-up giving you an advise about mulberries please disregard.