Hello there @ShadowWolf2190!
The error you are getting indicates that UE is running out of memory, as your system is taking quite a toll for a big project.
The first step to resolve the problem would be to close the engine, go to Control Panel > System > Advanced System Settings > Performance > Settings > Advanced > Virtual Memory, uncheck “Automatically manage…”, choose custom size, and set it to 32768/131072 (which is equal to 128 GB). After the change, re-open your project, and check if the crash is still present.
As for your setup, 16GB is a bit to close for engine work, specially in a demanding project. I would suggest installing more RAM (target 24/32 GB), and if possible, moving your project to the SSD, as working on the HDD will definitely affect your performance.
Finally, regarding the map, you can navigate to your project folder, and check the Saved folder for any autosaves or backups. There should be .umap files with old versions of your map, which can be tested in empty projects, for recovery.