2010 Chevy Malibu leaking antifreeze...used sealant no longer leaking what's the prob?

Could have been a hool

Did you use a additive in your antifreeze?

did you see any engine leaks? any water in the oil? you need to look for signs of where your coolant went.

too late! problem fixed , don't worry ,is good now

Good until when? If you had a leak, that indicates there is a weak link somewhere and the stop leak additive only masked it for a short time. It may of been your water pump and the weep hole was letting the water out, now you plugged it and your water pump may go at any time. You need to find where the leak was and get it fixed. It may of been a lose connection, water hose starting to let go, or the water pump, or head gasket. Like said above, make sure there is no antifreeze/water in the oil. Your oil will be milky in color if there is any coolant in the oil, indicating a head gasket is leaking. Was there any water on the ground under the engine? If so what was the location, which is where you should be looking. If all this is wrong, rephrase your question.