Njan ninte jeevithaththil undayathil nee khedhikkunnuvo? (ഞാൻ നിന്റെ ജീവിതത്തിൽ ഉണ്ടായതിൽ നീ ഖേദിയ്ക്കുന്നുവോ?)
In Malayalam, you can say "എന്നെ ജീവിതത്തിൽ ഉണ്ടാകാൻ നിന്റെ ശരിയായില്ലെങ്കിൽ പിന്തുണ ഉണ്ടോ?" (Enne jeevitathil undakan ninte sharayayillaengil pinduthunaundo?).
No. You can say "I regret not having checked that," or "You regret not having checked that." The word "for" is unnecessary.
Nee (ningal, thankal, etc.) vizhamikkum/khedhikkum/patchaththapikkum (വിഷമിക്കും/ഖേദിക്കും/പശ്ചാത്തപിക്കും)
Neeyanente jeevitham.
In Malayalam, 'for life' means "aajeevananthathekku/maranam varekku/ sthiramayittu (ആജീവനാന്തത്തേക്ക് / മരണംവരേക്ക് / സ്ഥിരമായിട്ട്)"
You have to say,"Jeevitham ethra sundaram"
I wanna spend my whole life with you
I'm not sure how to say that, but "I want a divorce" is "Saya mahu bercerai"
To say "kiss" in Malayalam, you can use the word "ചുംബനം" (chumbanam).
"I only regret that I have but one life to give my country."
" I only regret that I have but one life for my country."
A veces me arrepiento nunca haberte conocido (I think this means 'Sometimes I regret NEVER having met you'; and the question saying '....EVER....', you would use the same sentence minus 'nunca', since the meaning is 'Sometimes I regret having met you', the 'ever' merely a reinforcer).
In Malayalam we say 'dayavaayi' for the English word please.