The Hulk has brutally and savagely murdered all of Sue's childrens. Reed Richards is obsessed with bringing them back to life with his technology and locks himself in the lab day in and day out. The Thing managed to catch up to the Hulk but after hours of battle died at the hands of the Hulk. Johnny Storm has tried to get on with his life by becoming an actor but has recently taken up cocaine to quell his nightmares.
Through it all, Sue Richards has desperately tried to keep it together. For herself and for her family. She failed. One day on a self-help book tour for child grievance she happens to run into the Hulk during one of his rampages.
After Galactus killed the Thing and Torch, she blasted a hole right through G's chest without a problem...so yea...she is a lot tougher than people think.
In a fight with the Hulk, i could easily see a writer degrading her down to Invisible Girl and running away and hiding behind force fields in fear until the Hulk eventually beats her...he's really good at breaking force fileds.
Doom broke Sue's field when he had the ampified power of a Watcher behind his armor...I cant even explain how powerful Doom was in that issue...but the Intellect of Doom and more cosmic power than the surfer behind it? That just isnt fair...it was also the first time Sue's shield was broken.