I borrowed a vehicle and the engine got damaged?

Hi guys… I'm in a bit of a jam and i would like to know your opinion. I recently borrowed my wife s, uncle s van to conduct some business. The van is a late model ford ranger. He had the van over ten years now and it us used for work in his business. The vehicle isn't in mint condition or anywhere close.it just there, but not falling apart either. I borrowed the vehicle and upon starting noticed that both the gas and temperature gauge was not working. The owner gave me the van and I went about my business after about 1 hr of driving the van overheated and shut down. There was no warning signs or smoke until the vehicle had cut off. It won't start and has been two days. I haven't told the owner what has happened because afraisd I will have to buy back an engine now… But in my defense I could not have known that the vehicle was overheating because the temp gauge was not working… Go ahead tell me your opinion and what I should do please because I'm totally confused.

Did you check oil and water levels before driving it? A basic requirement before taking over any vehicle and a daily or weekly requirement thereafter depending on usage.
As it is the damage happened on your shift, your problem unless you can say the levels were good before you drove it.

What makes you think it was overheating? What, for that matter, makes you think you haven't simply run out of gas?

Have you tried to start it? If you can hear the car trying to crank over, then your simply out of gas

I think you owe them for an engine. Borrowing things is like this. There are risks

Either split the bill with him or you will lose more in the divorce proceedings.