How do you organize keywords for each page?

I exported all keywords from my competitors and had roughly 16k before going through them and ending up with 3k relevant keywords for my site. My issue now is trying to organize them based on my future page/category.

The only method I can think of is a regular Excel document:

category_keyword - keyword - volume - difficulty - CPC

It would look like this:

laptops - cheap laptops - 2000 - 10 - 5
laptops - best laptops - 1000 - 4 - 2
keyboard - cheap keyboard - 1500 - 10 - 5
keyboard - best keyboards - 2000 - 10 - 5

I still reckon it would be difficult to organize and annoying to add a new row for every keyword.

Any ideas?

I use a thing called "Treepad". Especially when structuring a website.

There are better tools for this out there surely, but I got used to this one years ago and used it till today.