I will pay you to go away!

Was moving from my house to live in downstairs apartment of my wife's elderly grandparents to save money and to help them out with property. Tried selling house from November to February (worst time to do so...). Had no offers so I had brilliant idea to rent it out. So, eagerly wanting to find tenants I held an open house and this couple with 3 kids walked through, said they loved the place and had cash on hand to give deposit and first months rent that day. I still had them fill out application and did what I thought was a thorough background check using a suggested website (thanks a lot google). All looked good and so I gladly took the cash. They wanted to move in asap so I busted my butt to pack and move out that weekend. They end up moving in 2 weeks early. Do they pay for those 2 weeks?, no. They are late with the first rent payment... oh great, good start. Following month, they are a few days late with payment... noticing a pattern already. Oh and he can't get a job because he was arrested on drug felony 8 years ago.. Then a few weeks ago they want me to sign this paper saying that there younger sister (who's only 18) is moving in so they can put power in here name. After many lies about the situation I decide not to sign paper, then all hell brakes loose. They only paid 1/3 of the rent on time and I still haven't seen the rest after 2 weeks being due. They call up screaming at my wife who had been managing the property. Upset because we want to do a walk through of the place and collect back rent. Then couldn't get in touch with them in any way... I needed them out!! So was all ready to start eviction process. Call lawyer, he wants $1k. Town wants $100. Court fees? Lost rent?... Option B, my wife reads about doing a "cash for keys" contract. I am paying them $2,000 cash to move out. As crazy as it sounds and as hard as it is to hand them money it is the only way to get them out fast and without damaging my house. He told my neighbor friend before all this that he would flood the place if I evicted them... real piece of work, both of them. So they have until July 1 to get out. They get half now and half when I inspect the place after they have moved out. I guess I'm not cut out to be a landlord, but then again after this lesson I feel like I have earned my degree in picking and dealing with bad tenants... It can only get better right? Not sure if I will re-list or re-rent. The extra money is nice... if you can get it.