Playing over the minor ii-V-i can be quite tricky.

Generally speaking, either the m7b5 chord stands alone, or used just with the Dom7th (which can assume various forms) or used in the full ii-V-i progression.

There are essentially 3 scales in which a m7b5 chord appears:

1) As the 7th chord of a major scale
2) As the 2nd chord of a harmonic minor scale
3) As the 6th chord of a melodic minor scale.

If we take a Bm7b5 these are the choices:

1) C major
2) A harmonic minor
3) D melodic minor

This is what they sound like: