Poshut Yid,
Interesting Cheshbon! I too probably blew that kind of serious money over the past 10 years on all sorts of Aveiros and could have spent that money better on Tzedakah, taking care of my family etc.
HOWEVER, think of it this way:
Since when we do Teshuva M'Ahava, our Zedonos get turned into Zechuyos, then so too all the money we spent on Aveirah gets turned into money we spent on Tzedaka and Mitzvos!
If that is the case, we gave so much Tzedaka over the past few years! It is the Zechus of all that Tzedaka that has helped me, you and so many others turn our lives around and become better children of our Father in heaven.
Don't let the amount of money (or anything else) get you down! Aderabah! Be B'Simcha for how far you have come in such a short time!
Chazak V'Emazt!