Is what happened a punishment from God for a sin not committed, and did the cousin take his right despite the questioner's innocence, and does she have a right with him, and what is the legitimate ruling concerning her ex-husband and her cousin, and does God reveal the right of the wronged?

A believer should thank Allah during prosperity and be patient during adversity, for both are trials for which one is rewarded. What your cousin and husband did by severing the marital bond and not fulfilling obligations is a grave mistake, and the husband is obligated to pay all dues. If you are innocent, your reward will not be lost with Allah, and you will receive your right from those who wronged you if you do not forgive them. Nevertheless, we advise you to be patient and forgiving, for that brings a greater reward from Allah, as "whoever pardons and makes reconciliation - his reward is due from Allah," and "whoever is patient and forgiving, indeed, that is of the matters [requiring] determination."