Having a portion of your sabbatical funds in the market wasn't a dumb move. It's a ten year period, which is a substantial amount of time.
Given that you're tempted to pull out now, I definitely would NOT put the other half in, but I also wouldn't lock in the losses and pull out.
Instead make a plan to transition to a short term AA over the next couple of years. Like for instance at sabbatical minus 12 months, S-12, sell 1/12 of your stock holdings every month. You could go to low duration bonds or a CD ladder.
Worst case scenario you just delay the sabbatical or find ways to save even more! First world problem for sure. :D