Excel 2007+ is limited to somewhat over 1 million rows ( 2^20 to be precise), so it will never load your 2M line file. I think that the technique you refer to as splitting is the built-in thing Excel has, but afaik that only works for width problems, not for length problems.
The really easiest way I see right away is to use some file splitting tool - there's tons of 'em and use that to load the resulting partial csv files into multiple worksheets.
ps: "excel csv files" don't exist, there are only files produced by Excel that use one of the formats commonly referred to as csv files...