Removed oil cap smoke came out?

My car which had an oil leak, and is a 93 Toyota Paseo was extremely low in oil and stalled out twice. Made it home added oil but upon removing oil cap, smoke came out. Next day added oil and stop leak and car died. What happened and is car fixable?

Oil was very low. Added oil along with a " stop leak" product. Car worked fine the day before although it stalled twice that night. Radio and other electric things work, but engine won't turn-over it just clicks.

Great site :-)