I will say, you are a good person for helping this guy. You need to set terms. "Look man, I know you and your child are in a bind and karma is telling me to help you out, lets set out a plan to get you to a point you can be self sustaining. You have 4 months to dig yourself out of this mess, during this time I will only charge you $100/month. If in 4 months you don't have a place of your own I have to tell you to leave, I cannot carry all of us." Man to man, no bull-shit, work something out and help this guy. Set a goal and don't waiver.