Please correct me if am wrong,
What is the appropriate way of expressing the past tense of pain
Should it be, "I am pained" or "I was pained"
The past tense of pain is pained, as in "it pained me".
What you are talking about is the passive:
present, I am pained by your disrespectful behaviour, or
past, I was pained by your disrespectful behaviour.
I think it is probably more common to use pained adjectivally:
present: I am pained to see you behave that way.
past: I was pained to see you behave that way.