Who or Whom in this sentence..?

Question

In this sentence, do you use who or whom?

One of my closest friends who I have been friends with for many years is ...

Answer 1

If you can say 'with' before it, it's whom. So:

One of my closest friends with whom I have been friends with for many years is ...

Whom is something that is the objective clause of 'who'. So to do something to someone, like speak to them would be. 'That is the person to whom I spoke.'

Answer 2

whom

Answer 3

use whom