The reserve bottle for antifreeze is broke in my truck?

Before you start it remove the radiator cap-fill it with the proper antifreeze protection stop when its about 1 in from the opening, Now start the vehicle up observe the level if it goes down fill it again till it no longer takes it put cap back On -you're done.

Here is a video that will help you check the coolant safety

https://youtu.be/GSE9skKnOgY?si=39tgGBA5QQicB5-F

Here is how to replace the coolant reservoir which would help the truck not overheat. Sorry to hear about your husband.

https://www.2carpros.com/articles/coolant-reservoir-replacement

Let us know if you need anything else.