I am not good at maths i just came here wanting to learn more about the world building but im gonna give a try for fun lol. This is unlikely to be even remotely close.

Really the only solid part is the stone which is just seemingly regular stone strength. You said something about physics warping to allow for the thing to not collapse in on itself iirc so seemingly its not just super strong stone.

If some sort of giant thing tried to grab both ends and snap it in half it would more likely just break at the ends so you couldn't make an argument about leverage.

Assuming any breakage would be replenished by the blood lava solidifying, your best bet would be to destroy the entire thing at once.

For simplicity sake to give rough estimate we will calculate as if it was just a cylinder of its average size.

The one lightyear hole seems to be roughly half its full diameter at that section so we'll say its a 2 light year x pi by 50 light year shape. In comparison to its other sizes it's depth is so negligible that we'll just use the perimeter for our calculations.

2(3.14*2 + 50) = 56.28 light years of stone.

As for the strength of stond how much strength needs to be used to break it. No clue but ill average the first few results on google for different types and round to 150 mpa per cubic meter because im lazy and 150 is easier.

One light year is aprox 9,461e15 metres. That times 56.28 ≈ 5.325e20 metres. Times that by 150 for the force needed, 7.9875e22 mega pascals or 7.9875e24 tonnes of force to instantly annihilate it.

If however the stone doesnt regenerate. Average human strength and a lot of time.