The translation of this dua?

When I am sitting down on my knees on the final rakat and after I have said durood e ibrahim, I say this du'a:

Allahuma inne zulamtu nafsee zulman kaseera wala yagfuruzunooba illa anta magfirahlli magfirahtum min indika warahamni innaka antas garfooroorahim.

I don't know the meaning off this du'a as I do not know arabic. I was told to say this about 10 years ago and say it in all my prayer before giving salam to the angels on the shoulder. I follow the hanafi Maddhab and I read online you can say any du'a after durood e ibrahim. However when searching for the meaning of this du'a, I couldn't find it. Anyone know the meaning/english translation of this du'a. It's been nearly 10 years since I learnt it and only know it through memorization and having recited it many times.

Translation:

"O Allah, I have greatly wronged myself and You alone can forgive sins, so grant me forgiveness from you and have mercy on me. You are the forgiving and Merciful One.

I have copied this translation from a post on IB, you can read the post for better understanding.

https://www.islamicboard.com/new-muslims/134272247-english-translation-salaah-prayer.html