Hey mr.buff, the way you explained it much time has gone by since this has happened. I will tell you my one very bad experience with attempting revenge without going into all the details, as I've posted this in SLR a while back. I'm giving you the long version, because the details are fucked and complicated. Sorry for the big read guys.
It was a boyfriend who was in the habit of borrowing my car for "work" and he always promised to pay me xx amount of money. Time and again, he never came through because the job didn't get finished or the person gave him a personal check he was unable to cash. This went on for the better part of a year, and I think twice he actually gave me some money. But after so long, I had to put a stop to it because my tires were bald, many thousands of miles and it was running poorly.
For various reasons, I was missing money. Car repairs that he could not produce receipts for. He had taken cash from my wallet when I was asleep. Promised he would repay me but that never happened. It's a big long story but boiled down to stealing from me. I phoned him after not hearing from him for a week and I could really use some cash and please just give me what you can.
So when I got there I walked in and was greeted with him slamming my head into the kitchen wall. Then being thrown into the pavement outside. He fucked me over and there was nothing I could do about it except walk away. It was my fault for letting it keep happening and that's what angered me the most. Fast forward two months went by and calls me out of the blue, he's lonely and just wants company. "I know you need cash and I can give you fifty, please I miss you just come over and we can hang out."
I took the bait, and he had no money but plenty of liquor. So we got drunk and watched movies all night into the next day. Sooner or later he needed to go to sleep because he was taking medication for his diabetic neuropathy. My inner cunt kicked in and some of his electronic devices disappeared. I went home feeling somewhat vindicated but that didn't last more than a day. He had it coming but at what cost, I could have gone to jail for that. He says, "We're even okay" and left it at that.
Strange as it sounds, we're still friends if you can call it that. After more than a year has passed from that incident, I can't hold a grudge. Like maxalfie said, it's not healthy. He phoned Saturday asking me to stop over because he hasn't seen me in so long. He needs to go back into hospital for more amputation and could use some company. The only thing I could come up with is, I'm busy maybe some other time. If there's people that owe you money, you can ask for it back, Good luck getting it after years have passed.