Among friends, in casual speech, the vast majority of native speakers, without so much as a blink, would simply respond
On the other hand, in very formal (and academic) writing
With whom did you want to speak?
Or slightly less formal
Whom did you want to speak with?
Yes. You can end a sentence with a preposition. Yes, you can use the subject pronoun "who" even when prescriptivists tell you to use the object pronoun. You're speaking to a friend, not to a poet laureate. Whom may not be obsolete but it's certainly closer to death today than it was sixty years ago.
who do you live with (blue line) with whom do you live (red line)