Milla, here´s another Finnish saying (sorry that they translate so awkwardly!):
A half-finished work should not be shown but to madmen and to lords.
WHY this should be so, no idea! But, maybe your husband will want to wait and see until your hair is "ready" ?
Once you´ve gotten rid of all the coloured hair and are completely gray (silver? Platinum?) you can decide if you love the look or not.
And, should you hate the way you look, it is very easy and fast to colour it again.
Have you considered you´ll have virgin hair then and can choose anyt colour in the world? You won´t be restricted by the colours you used to colour your hair into by any way.