You are right to be concerned about the condition of your incision and umbilicus. I'm a bit worried that you are on-line asking questions, but I will assume that you are getting "unofficial second opinions" regarding what your own surgeon is telling you. Continued follow-up visits, antibiotic therapy, wound care including possible surgical debridement (removing the dead tissue), and particularly examining your breasts to ensure the highest likelihood they do not become infected also are critical to this turning out well.
If you are a smoker or are exposed to second-hand smoke, this could be the CAUSE of the initial wound breakdown, and infection a secondary complication of the loss of blood circulation that nicotine exposure can cause. It's too late now to "bring back to life" the skin and tissue that have died from lack of proper circulation, but it's not too late to limit the amount of additional tissue loss and damage that both poor circulation AND/OR infection can cause.
This is why we constantly are telling our tummy tuck, facelift, and breast lift patients to avoid tobacco or nicotine in ANY form before and after these circulation-critical operations. And YES, even ONE cigarette or exposure to second-hand smoke can cause skin death that leads to precisely the kinds of wound problems your photos show. If you are a non-smoker and were never exposed to the bad effects of nicotine, this kind of wound problem can still occur from inadequate circulation, or when an incisional infection or stitch abscesses develop. The black appearance of your umbilicus and several areas of your central tummy tuck scar look more like circulation impairment first, then infection developing in the dead or ischemic tissues. Fat dies first, then skin, which is why your incision initially looks a little red, then "suddenly" opens up to the wounds that look so terrible!
All that being said, any surgeon who has done several hundred tummy tucks has occasionally seen wounds like this, and careful follow-up visits every few days at first, then at least weekly (more if needed) will get things healed up as quickly as possible, and hopefully avoid problems with your breasts or liposuction areas. This CAN be a big deal if ignored or inadequately treated! When it all heals, a fairly simple scar revision can improve the increased scarring this kind of wound healing problem will cause, though the final scarring will be surprisingly "not as bad" as the appearance of the wound will imply.
See your surgeon ASAP if not already doing so. Good luck and best wishes!