Unfortunately, the phrase "I love you, my sweet beauty" does not translate very well into French on a word-for-word basis, but if you want to express your love for someone, these are perhaps the best ways of doing so:
“Je t’aime mon amour”- This is the most common: It translates literally as “I love you, my love.” This does sound a little strange in English as the word “love” is used twice in one sentence, but in French the same thing does not apply.
“Je t’aime beaucoup ma/mon chérie” – This translates roughly as “I love you very much, sweetheart.” Use “ma” for a female and “mon” for a male.
Be careful when using online translators, as they will often suggest the polite, formal version of “you,” which is “vous.” This is what you would say to a teacher, a boss, or an older relative. It also happens to be the plural of “you” in French. "Tu" would be used instead of "vous" when addressing someone you are close to.