Our ds12 was grade accelerated and he is thriving.

One of the things you can point out to him is the danger of underachievement and how important it is that you both support and nurture your dd's profound ability. Especially now, before coping habits of hers become entrenched.

It is difficult dealing with exes, I know. Particularly if adversity has become the norm. But this is a potentially life-altering situation, and life-altering in a positive way for your dd.

Good luck!