The heater hose might well be .... the problem. Having found that needs replacing, and it is not a fortune usually, avoid spending on anything else until that hose(s) has been replaced and tried.
As regards do you keep the car. I was brought up "
olde school". If the body is sound keep the car, mechanicals can be fixed.
There are sometimes circumstances to make a different decision but surely most over heating comes down to something that can be fixed.
Only you know the arithmetic of having bought the car. And you might have an idea of the arithmetic of selling the car. That is all....your private business in my opinion.
BUT OVERALL that heater hose is leaking and you are replacing it so I would, wait and see.