Ich liebe mein frau, sie ist der beste! i love my wife, she is the best!
Well, it sounds like the gender of your wife is a bit grammatically mixed up :P
Ich liebe... - good!
...meine Frau - needs the form of mein- to match the feminine noun Frau. All nouns need to be capitalised, too.
(Then it's better to use a full-stop, I think. Or maybe even a semicolon!)
sie ist... - good!
...die Beste - here it's getting tricky, using a nominalised adjective. Basically you're saying ...die beste Frau but leaving off Frau and turning beste into a noun. When doing this to describe a noun for which the gender is known (as it is for Frau here), you need to make the gender match too.