All perfect praise be to Allaah, the Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
What we understood from the question is that you feel regret because of borrowing money with Riba (interest and/or usury) by using the credit card that is uncovered. There is no doubt that this is forbidden and you are obliged to repent from it by regretting what you did, seeking forgiveness and being determined not to do that again. For more benefit, please refer to Fatwa 86527.
As regards your work in the shop and what you earn from it, then that transaction does not affect it as the sin of a Riba-based loan is related to the person who borrowed the money and not to what the money was used in, as we clarified in Fatwa 93774.
Also, you are not obliged to give some of your money in charity but if you do so with the intention of repenting and getting closer to Allaah, then this is good, as the good deeds wipe out the bad deeds.
Allaah Knows best.