One nite my body became weird, my heart was beating so slowly and heavy. then i felt like i had left my body. did i die or an out of body experience?

Not likely depends: Not likely that you died - re out of body experience that depends on your belief system - if it includes this possibility then maybe - if not then unlikely - get a cardiac and pulmonary evaluation.

See GP: See your doctor. Unlikely u were dead because it is a irreversible process. Need to make sure that you don't have an abnormal heart rythm.