My kinsfolk have failed - My neighbors (קרובי qârôbāy), those who were near to me. It may refer to “nearness” of affinity, friendship, or residence. The essential idea is that of “nearness” - whether by blood, affection, or vicinity. In Psalms 38:11, it denotes near friends.
And my familiar friends - Those who knew me - מידעי myudā‛ay. The allusion is to those who were “intimately” acquainted with him, or who were his bosom friends.