It's true that the space between sentences should be larger than the space between words, as it is in properly typeset text, though not twice as large. Using two spaces is a way to approximate that when you only have monospaced fonts. It's no longer encouraged in electronic text when using proportional fonts because the rendering software _should_ adjust the spacing itself.

edit: monospaced, not proportional.

> Look at any printed media from the last 100 years.

I have, and it contradicts your point. The single space is the nearly universal standard in modern print media.

Sir, there are rules. You have to follow them. You don't insert arbitrary number of spaces after any punctuation marks. Your 'mental breath'/health issues should not affect others. Historical workarounds for quite technical problems from past eras don't mean what you think they mean. They were workarounds, not a valid reason to use double spacing in digital texts.