Subaru Engine Failure

I am sick. I bought an ‘08 Subaru Outback for $4k and
have had to put another $4k into it. The head gasket and
timing belt replacement was $2,400. That was done in
April ‘18. Last week, the car broke down and was pretty
much out of oil. We had the oil changed 6/1/2018. 3
mechanics told me that the oil change place must not
have put oil into the car. The oil change place showed me
video footage of them putting the oil in the car. Oil change
mechanic said that when the gaskets were replaced, that
mechanic should have changed the piston rings and the
increased compression probably blew the rings.

Anyway, now I am faced with the decision to cut my
losses and junk the car or do I spend another $4k on this
car and put another engine in it. (I’ll never own a Subaru
again).

I also put brand new tires on it. Can I somehow sell
those? They were $800.