Prior to jumping you should be suffocating in the bedrock.
How to make a hole in the nether roof.
Find a two block tall space to stand in just under the topmost block of the nether and make sure there is a two block wide or one block wide though it will be more difficult one block tall space in front of your eyes.
This will also work in minecra.
There are various different ways of doing this many of which are listed at tutorials breaking bedrock.
Once you have done this mark the coordinates of the trapdoor so you will always be able to get back there.
Go ahead and break a hole to the nether and put ladders in it with an iron trapdoor on top with a button.
Updated version for java 1 15 https youtu be sdlauladdwc in this tutorial i ll show you how to easily get on the roof of the nether and break a block in th.
Throw your pearl horizontally into this space and jump.
Help me get to 250k.