I know you feel you need to do this emotionally and mentally, but at what cost physically?

I may be the bitter naysayer in this It feels like you are neglecting 2/3 of what a triathlon is. Have you done any shorter distance triathlons? In your condition right now, would you be willing to do a 1/2 marathon or a full marathon? If not, do you feel that you could do it after 112 miles of bike riding?

Honestly, I would stick to something that your doctor would recommend. An iron-distance triathlon is not that. Many peoples' real abilities are crushed by their pride.