Water is mixed with oil.

I think you have a bad intake gasket. These engines,(vortec v8 and v6 ) are well known for this problem

You have a blown head gasket or cracked head or both. As you have been continuing to drive the truck you have done damage to the engine. How much damage can only be determined by removing the heads and the oil pan. At that point any good mechanic will be able to determine the extent of the damage. You will have to either just replace the head gaskets or if the damage is severe you will need to overhaul the engine. Another alternative would be to buy a new engine from GM with a 3-36 warranty. Do not purchase a rebuilt engine from any auto parts store. The quality of these engines is dubious at best. If you live over a few miles from a trusted mechanic have the truck towed in. If you live close drain the oil, put in 4 fresh quarts and drive it to the shop. Until you can get it to someone for repair, stop driving it and change the oil immediately.

You do have a problem. The engine has a bad head gasket or some other internal leakage . It usually is the head gasket. Dont run the engine with that much water in the oil. The oil is diluted and will cause bearing damage. Overhaul will then be needed. Starting hard is due to excess fluid in the crancase. The cooling system needs to be pressure tested to find the location of the breach.

take it somewhere and have a block test done. most likely a blown head gasket

Fix this ASAP, Coolant in oil will ruin bearings. Have a shop check it ASAP. I would check the intake manifold gaskets first.