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If you mean that you don't like the automatic space that is added after dots or words, you can turn this off from Settings -> Language & input -> Xperia keyboard -> Symbols and smileys -> Automatic space (disable).

it's also 'only' that smiley it happens with)
The first option with automatically correct typos without giving suggestions, can you switch to second option and try to type it again?
it's 'never' corrected into something else than what it suggests.. I've used this setting since smartphones came out pretty much, I've never encountered this problem before.. The smiley-problem started a few weeks ago only
If it was working fine then messed up suddenly then I'd suggest that you refresh your keyboard app (Note: keyboard setting might reset so you'll have to reconfigure it):
- Go to Settings -> Apps -> All -> Xperia keyboard -> Force stop, Uninstall updates, Clear data and restart your phone
- Go to Play Store and update you Xperia keyboard again.