If it has developed a good root system (will have a long tap root), then just plant it in well draining potting soil. Often water is just used to start the germination process, but once the seed has germinated (producing growth from both ends of the pit), it needs more than water to keep happy and healthy.

a nut.. or seed or whatever an avacado is.. lol ... is just an energy storage system.. to allow the seed to sprout.. and get a root into mother earth ... and once the roots are down ... its not really necessary for the plant.. and eventually shed ...

you have roots... and now you have it in soil or media in a pot .. so in theory.. the seed food source isnt necessary ...

all that said.. your plant is probably in total shock ... not only from moving from water to soil ... and all that .. but also from the rough handling ... i would expect it to look a bit stressed for a few weeks while it recovers ....

since it is stressed.. i would keep it in full bright shade .. until it settles down ... eventually moving it into stronger sun.. which most trees need ...

ken