Won't it still be washable with the acrylic on it? I've made lots of stencilled t-shirts using acrylic paint and they come through the wash just fine - although I heat-set the acrylic with an iron through the inside of the shirt before wearing the first time.
You could always give it a shot, if you like!
Oh and very cute, btw
I like it, I really need to catch up with Heroes.