Male perspective- I have my father in law living with us. When is enough enough?

I feel like I have no options. Or at least no good ones. Here's the back story. My MIL and FIL were living on their own doing fine (as far as we knew). They were almost done with their mortgage payments and would soon completely own their house. My wife's sister and her family moved in with them because basically they were evicted from their rental property for not paying. So my in-laws had themselves and now 2 adults and 3 kids living there. This arrangement went on for 2 or 3 years. In the meantime, my wife and I are living with my parents so that we could save money for a down payment on a house. I had never moved out of my parents before and they didn't want us to rent. It wasn't a perfect situation to say the least, but the end was in sight. We managed to save up enough money to buy our own place and were going to start looking soon. We went over to my in-laws for a coffee and a visit. Here we are told that they are losing the house and are being evicted. Nobody was making mortgage payments there?! There are 4 adults in the house and they didn't make a payment? Crazy right? They were all out of warnings and they showed us the final paper. The sister was all stressed out and decided to go camping with her family while this got sorted out. It didn't get sorted out and they lost the house of course. The sister and her husband's financial situation didn't change and somehow they managed to start over with another rental house in a different town. They left their oldest child (15) and her Mom and Dad to figure this out on their own. So, my in-laws who weren't working at this point went on welfare and found a cheap place to rent a short distance away. I should point out that my MIL was sick from cancer and wouldn't be able to work. My FIL was young and able, but never had to keep a steady job in his life. After a few months of them living there, it's clear that they are living in poverty (except for smokes.... there's always money for smokes), and that my MIL's health wasn't doing well there. My wife and I decided to look at places in the city and my wise idea was to see if her parent's wanted to move in with us so we could help look after MIL. ugh. I knew it wasn't a good idea, but my wife and I were on top of the world. We were so excited to be buying our own place and stepping up in the world. How could we share our excitement with her parents without feeling awful about what they lost? So, we move in together. Life is far from easy and we all have to adjust. And now that they were living with us... low and behold and look who finds a rental in the city? Yup, the sister. Just a block over from us to boot. At least she'll help with them right? LOL. Sadly after 5 years of them living with us, my MIL passed away from a surprise diagnosis of stage 4 cancer. It's been a year since then, and my FIL is still living with us. I wouldn't mind him living here, if he pitched in with things around the house. He pays $300 "rent" to us. Has virtually no bills and receives $1600 per month from old age monies. But somehow, the bank gave him credit cards and he wracked up $9000 in debt. When he first moved in with us, he got a job. He must have got tired of it, because he just quit going one day. They'd call and he would pretend to be sleeping and not get up. Once he did get up, he would act like what he was doing was normal. I'm sure I didn't explain everything quite right, but now you're all caught up. My MIL passed away, like I said, about a year ago. My FIL is only 67 and retired (good for him). Unfortunately, he doesn't do anything around the house as that was his wife's job. No, sweeping, dishes, cleaning, nothing. He will do outside work, like cut the grass and shovel snow. But it's winter, and we haven't had snow to shovel in weeks. We've asked him to help out with inside stuff and he simply refuses. He tells us that he can't afford to move out and he'd be homeless if we kicked him out. He's an opinionated hot head who starts talking loudly if he doesn't agree with something, which is often. I can't speak my mind around him, because it'll set him off which upsets my wife. My wife can't wait for him to be moved out too, but she refuses to have a rational conversation without becoming defensive for some reason. I want a game plane. He could live for another 20 years and do we really want the same thing for 20 more years? Something needs to change, I'm just not sure what. So, basically, my advice if you ever are thinking of moving your parents or in-laws in with you... don't. If they were sick and only had a few years to live, then yeah I would. But this guy could outlive me for all I know. And I don't mean to sound ungrateful. I know we're lucky to have been able to get to know them better and to improve their life style over the last few years. But when is enough, enough?