First do the easy things
1. with the car OFF
Check the oil- is it milky?
Remove the radiator cap- is it milkshake? Oily?
remove a few spark plugs- is the electrode and porcelain whitewashed from coolant?
2. Start the car with the radiator cap off
When the car starts to warm up grab the top radiator hose to see if it starts to heat up and you can feel the thermostat opening. If you can squish the hose with no feeling of warm water inside coming from the engine, then the thermostat is not working.
If the thermostat starts to open, do you see bubbles in the coolant? Does the car start to puke out anitfreeze? Is the coolant level very low? If so fill the radiator and check for bubbles, milkshake
Replace the radiator cap
Does the exhaust smell sweet or like coolant?
Water dripping out the exhaust
Car temp rise quickly and/or overheat?
3. Rent an exhaust gas coolant detector kit. It is a large tube with a bulb on top that goes into the radiator cap opening, You fill the tube with a blue chemical. With the car at normal operating temperature and the tube in the radiator cap opening, squeeze the bulb to draw the air from the top of the radiator through the tube, If the chemical turns green, you have exhaust gas in your coolant an a bad head gasket(s).
Sounds like you blew a head gasket and you have coolant in your oil. That can wipe out your rings and bearings in short order. Do not drive the car much if any until you diagnose the problem.