I understand what 'you two-timing bastard' means. I just can't explain the lack of the verb after the pronoun.
It's an invective in the form of addressing someone.
You can address someone without a verb. It tends to be more often negative than positive.
You bumbling idiot!
You wonderful, sweet, darling man!
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.