Cracked head gasket for sure? 2005 Chevy Impala 3.4L V6 163k miles?

[Jordan]

I have an overheating problem in my car. My engine runs for about 10 minutes then goes straight to the red without any circulation going through the car. I get absolutely no heat coming through my vents and the car will not drop from 260 (max i.e. red zone). I replaced my heater core, flushed my system twice, replaced the coolant, replaced the water pump and replaced my thermostat x2. It still won't fix the issue. I have to put more coolant in the car every time I bleed it, so I have no idea where that goes when I do drive it. Once I bleed the system for about 30 minutes I can drive the car for about 10 miles or so with heat coming out of the vents in surges and very jumpy temps (between regular (200) and 245ish) before it starts to go back to 260 and stays there. I don't see anything dripping out of the exhaust, but my brother says my oil looks milky. When I don't bleed it and let it run in the red zone, I can see bubbles coming through my coolant reservoir as if it was boiling, but it is NOT hot at all. If it is the inevitable, a blown gasket, would it be better for me to replace the two gaskets myself or replace the entire engine? I just want to drive again...