What if you first just look at photos of ballons and then,e eventually, have someone you trust hold a balloon near you until you can stand that. If that goes well you may want to hold it yourself. Babysteps.
I know, I have a snake phobia and we have them all over our rock wall in the summer. Can now look at pictures and can watch my husband pick one up (garter snake-not a poisonous one) but haven't gotten to the hold it myself point.
Good luck & let us know how you do.