'I was bullied' implies further in the past or with more of a break with that experience than 'I have been bullied'. 'I was bullied at school' (this is now over) 'I have been bullied all my life' (this experience could happen again or is affecting my present) In some way or other, 'I have been bullied' implies a connection with the present; 'I was bullied' implies there is a break with that experience. For instance, 'I have been bullied' might mean you are still traumatised, or that it happened very recently. 'I was bullied' might imply you are over that experience now or simply that it doesn't happen any more. We also use 'I have been bullied' to talk about life experiences (i.e. looking back into the past from now). So it could simply mean, in my life I have experienced this before.