I am not surprised that you are confused. If you are just trying to use "it is" in a sentence, you have unfortunately chosen a type of sentence that is very confusing in English! It confuses English speakers, English teachers and experts in English grammar! If you search online you will find long arguments about this type of sentence. English grammar is not perfect, and in some cases that is helpful because it makes the language flexible, but in other cases it creates this type of confusion. In many European languages things (represented by nouns in the language) are either masculine, feminine or neutral... Everything in Latin languages are either masculine or feminine. And some of our grammar rules derive from Latin. In German many things that aren't actually masculine or feminine do have masculine or feminine nouns (and pronouns) and some of our grammar rules derive from German. Okay, we also have 'he' , 'she' or 'it', but in English very few things can be 'he' or 'she' ... basically just people and animals and other things we personify (for example people often use 'she' when talking about a boat). So it's really difficult, philosophically speaking, for English native speakers to think of a sentence like "It is you that are/is my husband" because we don't want to use "it" to describe "husband"... because "husband" is very clearly a noun that uses "he" not "it". If you only want to make a sentence with "it is" then I suggest you choose another noun that is not masculine or feminine in order to keep things simple. For example "It is my book." Apologies if I am explaining things that you already know.

I think... That 'is' follows 'that' when it refers to something singular and 'are' follows 'that' when it refers to something plural. Therefore, 'that is my husband', 'that is my dog', 'it is racing that is expensive', but 'it is the houses that are green', 'it is boxes that are cheap', 'it is cars that are noisy'.

We just say - you are my huaband.

Hi Lee The second one is grammatically correct and native speakers say "You are my husband".