Regardless of whether there was sexual contact between you and this other man, you completely betrayed your wife's trust. You were a willing participant in a sexual act regardless of what you may claim. You played a visual stimulating role instead of a tactile, interactive role. You don't say whether you were unclothed as well or whether this was a stranger or friend. The fact that you did this for money adds another complicating layer. Sexual activity for payment IS technically prostitution. Your wife has to wonder if you'd do this, what else have you done or what else would you do?
You broke all kinds of personal boundaries here, friend. Your wife has to be shocked, ashamed, terribly disappointed, and very angry. You must do some soul searching. If it's a shared money situation (which with spouses you'd assume it is, right?), then she has to understand what a terrible predicament you found yourself in. She felt and feels the financial desperation, too. However, she's not engaging in prostitution, is she?
I'm thinking there's something else going on that affects chiefly your finances. Consider what the root cause was behind your desperation. Although money was your surface need or motivator, I'm thinking that drug addiction, gambling, or some similar personal situation was the real driver for you to cross such a moral line. That is what you need help with. Go to her and ask her for help with that (e.g., rehab, counseling). Make sure she knows how much you care. If you've never had intercourse outside of marriage, say so and ask two things: marriage counseling and how to make this right by her.