Small Business Administration website (https://www.sba.gov/category/navigation-structure/starting-managing-business/starting-business )"21 Things I Wish My Broker Had Told Me" by Frank Cook (Dearborn Real Estate Education 2007)."

You most certainly can sell the building before it is stabilized, but buyers will discount the validity of the buildings performance.So, to figure out the {potential} value of the building you need to:1) Determine your revenue:determine what is the market rent for each unit type in the building and calculate your scheduled rent;determine the market vacancy for the area (for each unit type) and calculate your anticipated physical vacancy;Subtract the second from the first above and you have your {projected} effective gross revenue;2) Determine your total operating expenses:These include: property tax, insurance, yard maintenance / snow removal, electricity (house metre), oil/gas (if common heat); water/sewer, garbage collection; janitorial service; maintenance (10% of effective gross revenue); Property Management (7-10% of effective gross revenue); advertising, accounting & administration, etc.3) Calculate your Net Operating Income (NOI): Effective Gross Revenue - Total Operating Expenses4) Now you need to determine/learn the price being paid for similar (i.e. same class of building) cash flows in the local area.  

THEN I read in the paper that she has been arrested, with her boyfriend, for distributing drugs. 

Meaning you have a 10% of taxable income cushion to pay for the administration of the REIT. 

It had been a drug house at one point but had since been vacant for years. 

I mean, sure there are probably upstanding citizens as well, but downtown Clarksville is the opposite of what we would consider a safe investment. there is a lot of crime concentrated near the river and a lot of drug use.

I have been unemployed ever since because telling HR managers you are a former online poker pro is apparently akin to telling them "I'm an A-list porn star who also sold drugs.").

I lent money to the corp. to buy those houses and the corp. is supposed to reimburse me 5% of what I lended every year (to get my money back in 20 years if I am still alive...).The problem is that the corp. is of course unable to give me back money for now ; it’s not that much for me but it is for my children who carry that debt (declared to the french tax administration).

My Dad owns a house that squatters broke in and started using it for a drug house.  

I don't think this would work for your current situation, generally 401k administrators won't let you roll funds out of the plan until you separate from the company, and I doubt that you have substantial funds outside of your current 401k at 29 (although if wrong, then you're a rockstar and awesome at saving for retirement.)