Colour B4 on very damaged hair

Hello!

I dyed my hair brown after a failed attempt at blonde and ended up with extremely damaged hair. I didn't take into consideration having bleached then dyed my hair a year before, so from the ear down my hair was so soggy and gum-like I wanted to just lie down on the floor and cry after each wash. I've been pampering it for a while now, I go as far as I can between washes (ew) and deep condition and treat it with K-Pak every time I wash it, and eventually it started to resemble hair again. It's still a bit soggy when wet and it takes hours to dry, but it's not nearly as bad as it was, thank God!

However, the dye I used is starting to fade into a gross orange-y colour, which looks horrible with my skin tone. I know I should leave it alone as much as possible (or preferrably just cut it off, lol) but I'm itching to lift the colour and re-dye it with a more suiting color, similar to my natural dark blonde/light brown hue. For the colour I'm thinking Wella Colour Touch, as it's the only one available in online shops here and I've been told it doesn't damage the hair.

So, my question is; does anyone have any experience with Colour B4 on very damaged hair? I know it doesn't damage the hair in itself, but my hair is very fragile and I'm worried the drying effect will cause it to snap.