Failed Head Gasket

I bought a car with credit from the Bank. It was a Toyota Rav4 2000. Since I bought it,I had problems. First it was the turbo,than tires,and some other issues. Anyway 1 year ago,i needed to do a head gasket job that costed around 1.200 euro because oil was mixed with coolant. Now after 1 year,my mechanic told me that the engine has failed,because it is burning coolant. No mixing oil or coolant. I need an used engine and will cost around 1200-1300 euro. I still have 1 year of payment to the bank. With a 2 years old kid,and another one on the way I can't afford this payment,but I really need my car because I drive around 30 km each day to go at work.

I really hope that someone out there can help me.Thank you.
Endri Katro