I read once about a man saying he lost so much blood as a result of stress and ended iner for blood transfusion to stay alive.how is this possible?

Did not happen: not the whole story. Just stress doesn't cause bleeding. If he had a hemorrhagic gastritis or a bleeding ulcer, which can be exacerbated by anxiety or a difficult life situation, then that is why he bled. Stress is actually your friend when it leads you to learn new skills or achieve at higher levels. If you experience "bad stress" from an abusive situation, get out.