I would like to know what would happen to me if I report it to the university after I graduate or if there is anything else I can do about this situation without ruining my future.
Both your own actions and the actions of this other student would certainly amount to serious academic misconduct. It may also amount to some species of criminal fraud, such that it could also be a criminal offence. If you would like to get reliable information on this, I suggest you go and see a lawyer in your jurisdiction.
In terms of what would happen to you if this became known, I would think that you would be found to have committed academic misconduct, and some substantial penalty would be imposed. It is impossible to say what penalty would be imposed, but it could entail rescinding your degree. On the other hand, your adverse financial circumstances might count as a mitigating factor, and so it is possible that a lesser penalty would be applied.
Whether this would "ruin your future" depends largely on your ability to change your future behaviour and bounce back from adversity. I don't believe that a finding of academic misconduct ---or even a criminal conviction or loss of a degree--- is necessarily ruinous to one's future, but others may have a different view.
It makes me incredibly angry that you can just buy your degree like this when you are rich.
There is no valid cause for your anger. You have facilitated precisely this behaviour. Without the actions of people like you, it would not be possible for the rich to buy a degree. We can be angry about it, but for the time being, you have lost the right to be so.
Perhaps when your own conduct is more remote, and you have had some years to reconsider this episode and lament your own participation in it, you will once again have standing to feel anger over the short-cuts taken by the rich. For now, perhaps you should reserve some of that anger for people like yourself who defraud our educational institutions for money.