My refrigerator went out. And so I boiled a chicken and have had it on simmer/slow boil coverered going on 3 days now. Is it safe to eat?

it's safe, but it is going to be dry like heck. remove and dog or trash is my suggestion. use liquid for stock.should have great strong chicke flavor and will make foe some wonderful cooked gains or soup or sauce. chill first and remove the hardened fat on top.
a lot of cooks use whole chickens to make their stocks.