Besides and Beside

I started to keep a diary in this blog.I realized several things.One
of them is that the dictionary made of paper is better than the
electronic dictionary to look up words which I don't understand how to
use well.

I'd like to practice to find out "Beside" and "Besides".
I confused "Beside" with "Besides".

(I'll try to make sentences to understand.So it's a fiction story.)

I saw my girlfriend was walking with an another guy beside a river.
I was so beside myself with sad that I couldn't understand "beside"
and "besides".
Besides it,she kissed him beside me!!(She didn't realize I was beside them.)
I don't have any bad memory besides it.

(That's it.)

Does it make sense?
When you feel it's weird,just let me know,please.

-------------It's for my information------------
Merriam-Webster Online
"Entry Word:
besides
Function:
preposition

Text: 1 in addition to <besides me, there are five people working on
this project> Synonymsas well as, beside, over and above Related
Wordsplus; including Phrasesalong with, together with Near
Antonymsexcept (also excepting); less, minus 2 not including <your
essays should be three pages long besides the bibliography> — see
except"
http://www.m-w.com/thesaurus