So sorry to hear about your mom's troubles, honey!! My husband had a stent over 2 years ago, and he's doing just fine! He had his put in on a Tuesday, and on Saturday played a wedding with our rock band!
They have done amazing things with coronary artery disease treatments. Your mom will be OK, really. This will change your mom's life, and yours too. Not all of these are BAD changes: this was exactly the reason my hubby and I changed our eating habits.
Hang in there honey, and make sure you take care of you, too, during this time of high stress.