If I am talking to somebody about a certain group of people in the third person, and then want to refer to the person I am talking with as one of those people, do I say, 'One of them were you,' or 'One of them was you'?

If I am talking to somebody about a certain group of people in the third person, and then want to refer to the person I am talking with as one of those people, which do I say?

One of them were you

One of them was you.

If I am talking to somebody about a certain group of people in the third person, and then want to refer to the person I am talking with as one of those people, do I say, 'One of them were you,' or 'One of them was you'?

Thanks in advance!

If I am talking to somebody about a certain group of people in the third person, and then want to refer to the person I am talking with as one of those people, do I say, 'One of them were you,' or 'One of them was you'?