What do I do now about my car?

I bought a car and my dad bought a mechanic that he's friends with. He did a tube up on the car I've spent around 600 plus dollars on it already on other parts. So now the car is blowing white smoke and he tells me it's the head gasket. I bought the car for $2000 and is one of the stupidest choice that I made ik. It's a 1997 honda civic ex. I think it would've been cheaper to replace the motor. Any advice?

If it's blowing steam out the tailpipe plus losing coolant plus overheating, then yes, I'd say it's a head gasket problem too.
I would suggest you get a proper estimate so you have all of the facts in front of you.
I would also suggest that you consider doing the timing belt and water pump at the same time, unless they have been replaced recently.

Replacing the head gasket will be much cheaper than another engine.

Mechanic would have noticed the head gasket right off(as you can't do a tune up if the head gasket is leaking.) so stuff it back in his face as it should have been something he should have done right off. His tune up is BS and he knows that.
. Kinda of not a good mechanic because all know that,
. Cost of a head gasket is way less than cost of a motor and a lot less work to do.

Getting a used engine installed might indeed be smarter but not cheaper. I would ask then follow whatever dads mechanic friend thinks you should do. Have him give you a few estimates on your options.

Buying a very old Honda (or any other really old car) without a warranty is always risky.

It would NOT be cheaper to replace the motor.

I wouldnt have paid 2000 on any car older than year 2000, i got a civic for 2100 year 2000. That car will give you nothing but problems, stop putting money in it n put it up for sale

Your head gasket might still be good it could be your pistons that's causing the problem