How safe is it to have tummy tuck and breast reduction at the same time?

In a healthy patient a combination of breast reduction and abdominoplasty is safe. Your surgeon will discuss the specifics with you about convalescence.

It is common to operate on the breasts and abdomen at the same time.  Your liver disease must be checked out before proceeding with surgery  Please discuss this with your surgeon and your internist.  Sagging of your breasts will happen, but reducing them will certainly make your situation better.  If they are reduced, they will likely never be as saggy as they are now.