I dont think they will wash out, in fact they will most likely hold
together
very well because your hair is in such rough shape, which will make it
hold
its knots and rats well....;0)

My hair is also very highlighted....but not over processed to a point
that
renders your hair spongey, strange feeling, and falling apart when
wet....

Until you dred, just keep it really well conditioned and treat it nice
so
that you dont break off more hair.
Get some deep conditioning treatments....
Nemaste,
Moon