Well done. You were leading and unflappable and that built up enough trust inside her to allow her to reveal her private thoughts. Again, well done.
My W has the same problem, twins and then a huge third son (I'm 6'9" afterall) has left her abdomen quite a mess (hernia down the middle, super wrinkly). It doesn't bother me, but she is very self-conscious about it.
The ladies are obviously a better source for "what next" than me. Maybe ask her what she needs to help her feel better about her body? Don't suggest anything outright, unless she sincerely asks (it could easily be twisted into an attack). And then if it is something within your power, do it ASAP. Like if she needs some exercise equipment, a club membership, wants to change the diet, even surgery. My W's abdomen will never look "normal" again unless she has surgery. I would never insist on that, but if she wanted it, I would find a way to budget it.
JMHO
Chrome
"Recollect me darlin, raise me to your lips, two undernourished egos, four rotating hips"