Tummy tuck incision opening, white inside! HELP (photos)

You could discuss with your surgeon the option of excising and debriding this area and closing it again.  There may be too much tension to do this at this point but eventually once the swelling resolves it should be an option.  This should give you the best scar in the long term.  

Unfortunately, this occasionally happens. Typically good wound care until it fully heals is the management. This can take six to twelve weeks and does typically look worse before it looks better. You'll be amazed at how well it ultimately heals. There may come a time when your doctor will change to a cream called Silvadene to clean it up better during the process. Avoid smoking/smoke/nicotine products, keep it clean and eat a healthy diet.

Appears as a delayed fat necrosis with wind edge dehiscence. Local care as you are doing plus I might try PRP infusion therapy with laser red light treatments (fee $800 per session).