Any idea how to fix it? The metal around the latch has fractured. Thanks in advance

Door sags because the pins are messed up.

If i make a hard right my driver door flies open 😀

 

You need to cut out and weld a patch into the body pillar. You also need to make sure you have the backing plate behind the skin in place. To be honest, your latch looks to be in serious trouble. Might want to make a trip to a body shop to have it done. Call ahead to hopefully find a shop that has done this before.

 

Don't remove the broken latch post panel as it is, you'll need to keep the dimensions as they are, but inside the B-pillar is free to mess with.

I'd scab another overlapping piece from another GM truck of the same vintage - and weld or braze it inside the existing cracked skin.

Then, braze up the cracks, making sure to include the inner new piece by brazing it into the existing outer piece.

Etch, Bondo, sand, prime, sand, paint.