I am very worried my little sister's pet rabbit will die after being terrorised by our cat?

Please I would love anyone's advice. Today I was cleaning when I heard some squealing from my little sister's bedroom I ran in to find our cat with his paws through the cage of my little sister's new pat rabbit Misty. He had his paws clawing into the sides of the 6 week old rabbit's head and was trying to bite his face through the bars. I completely freaked out grabbed the cat threw him out and slammed the door. I ran back to find Misty sitting meekly in the middle of the cage. I picked him up sat down and hugged him close to me soothing him and reikiing him for about an hour. Apart from a slightly red and scratched left eye and being a bit skittish he soon calmed down and seemed completely fine. I let him run around all the while soothing him with some pats and strokes. It is now a few hours later in the evening and I am terrified that I will wake tomorrow to find him dead after a story that the breeders who sold us Misty told us about one of their rabbits emitting what is known as the "death scream" and then dying the next day. What I heard doesn't fit the description of what I have gleened this sounds like from reading some blogs and Q and A's on here (blood curdling, harrowing) but he is only 6 weeks old so maybe what he was squealing was as loud as he can go. He seems completely fine but I am afraid that he has scared himself into some internal problem that could cause him pain or death. Please if anyone has some advice I would be so grateful.