I was riding my obsidian laviathan in the nether

• all seats were filled with striders
• both saddle and tack equiped
• it was full health

I decide to quit. I wondered if the game would load the world riding the laviathan or just plop me in the lava so I load again.
Laviathan is gone, I sink into the lava.
I can't take damage however, can't place blocks, and can't break blocks.
Mobs do still move around.
Every subsequent quit&load will put me in the original position of the Laviathan.
Please let me know how to fix my world, if possible.

/kill fixed the problems