How possible is it for a hernia to rupture and have you bleed to death from it?

Unlikely: It is unlikely for a hiatal hernia to rupture.

Strangulation: Hernia's would be more likely to strangulate vs rupture. this can lead to that area of tissue dying. this is an emergency. Hiatal hernia's are very rare for this problem to occur, but inguinal hernia's have been associated with this problem. A hernia is a projection of one organ into another organs space via a weak muscle/fascia, etc. Suggest seeing General Surgeon for evaluation