got shoved on my 3bet 200bb deep vs a fish

Villan had the 50vpip-8pr-0 3bet
he RI 3.4bb and i have KK and i 3bet to 12,the stats are from 50 hands on gg
what i do there? ( i wasnt sure if he will ever overvalue his QQ/JJ/TT since he seemed a bit lost alot of the times)
it was a 6max table on 25nlgg