Felt is the past tense and past participle of feel. The past perfect tense of feel is had felt.
"had felt" is in the past perfect tense. It is used to show an action that occurred before another action in the past.
(subject) had felt
The past tense is 'felt'. The past pluperfect is 'had felt'
Existed is the past tense. The past perfect tense is had existed.
The past tense of feel is felt. For example, I felt sick. Or, I felt the cloth.
There is no past tense for "felt". "felt" is the past tense of "feel". "You feel good today, but you felt bad yesterday."
The simple past tense (and past participle) is felt.
The past tense is bled, and the past perfect tense is had bled.
The past tense of sit is sat; the past perfect tense is had sat.
The past tense of "feel" is "felt."
The past perfect tense is "had confronted".
The past perfect tense is had chosen.