Whatever the outcome, you will probably be fucking people over. If you're alright with that, continue.
Obviously, there is a high probability that you will be caught and prosecuted, as many people have already pointed out. If you're alright with that, continue.
If you're not sure what to do with the data, the easiest route would be to find a buyer who does. It's up to you whether you want to know what they plan to do with it, though your liability might make you just a bit curious. There are definitely ways to reduce your risk and distance yourself from any nefarious activities (though you have already perpetrated a grave one by stealing the data itself).
I personally don't know enough to direct you in any way, but there are certainly people here that could.