I am not sure if i ruined my Mazda Mpv Engine How would I know help !!!!?

[tl082002]

I just bought a cheap 1995 Mazda MPV 6 clind & drove it 10 miles & parked it for an errand & heard a hissing sound under the hood & notice water draining from the car & steam I had to drive it home & then the car overheated w/ a bad burnt smell & smoke from under the hood The next day I took it to work 7 miles & on the way to work it happened again I put lots of water in the coolant & radiator & drove it to a mech after work He has not checked if fully but now he's saying I need a New Engine that will be $1000 I can't afford that Could I use a Engine Sealant to help? HELP me experts please !!!