1999 Nissan Maxima What to do?

So I took my car in about a while ago because I was seeing some minimal smoke and the car was overheating. The mechanic told me my thermostat electric fan was broken and that it would cost me $1000 to repair. I couldn't afford it at the time so I put it in my friends driveway and didn't touch it for almost two months. I took it in today, only a 2 mile drive, and the guy told me that my head gasket had blown because of a radiator leak and that it was either get a new engine or pay $2300 to repair it all. Is he trying to screw me with the prices? And is what he is saying sound like what could be happening to my car? I don't want to pay this much. Also, can any of it wait to be repaired or is it necessary for repair?