Given the mess that it was, I would open all the low point drains, and also drain the water heater. Get the system empty. Close the drains. Refill the water tank about halfway.
You want 1/4 cup of regular bleach for every 15 gallons of water. Mix this amount of bleach into about a quart of water. Pour this into the water tank. Finish filling the water tank. Remove the bypass from the water heater so it will fill. Turn on the pump and run every outlet, hot and cold, until bleach water comes out. (This will take a couple of minutes.) Then let it all sit for 12 hours or so. Don't double up on the bleach.
Then drain the system, fill with fresh water, and run all the outlets until water comes out. Then run them until the tank is almost empty. Repeat. You should be OK after the second rinse. The extra rinse will get all the bleach smell out.
You should also sanitize your hose. Not a bad idea to do this first. Put a couple of tablespoons of bleach in a cup of water and pour that in the hose. Fill the remaining hose volume with water, screw the hose ends together and let that sit too. Rinse thoroughly.
My condolences on the loss of your wife and son.