Hi there. I USED to be a decently successful investor (until 4 internationally adopted kids turned my world inside out!!). However, I have not been 'active' in almost a decade and am not only unsure of myself, but also I know the environment (and therefore 'rules', if you will) have changed significantly.  I have a question related to one of the 2 investment properties left in our portfolio....here are what I would consider the relevant background details:

- We are a family of 6 (me-46, husband-55, 4 tween/young teens) and we lost everything in 2008-10 including all we had for our retirement plans
- We currently own 2 4-plexes; 13 yrs left on mortgages; very minimal cash flow now, but no out of pocket expenses either
- Our plan has been to keep those 2 4-plexes knowing than when mortgages are paid off, the cash flow will at least keep us out of working at Walmart as senior citizens!
- Our plan is to purchase additional multi-family investment properties as soon as we are able to expand our portfolio as that will be our only shot at a decent retirement....based on our ages, however, that will have to be done quickly and with 10 year loans which means we will need LOTS of money for down-payments....I homeschool our 4 kids (3 with special learning issues) and my husband is trying to build a new business after the one he owned/ran for over 12 years died a couple of years ago....could easily be 5 more months before we see any income so at the moment, conventional financing is not going to happen for us

Here is my question: I was recently contacted by an investor who wants to purchase one of the 4-plexes.  SHOULD WE SELL?  My fear in doing so is that getting into something now with as much equity or at today's values will NOT be easy (probably worth about $600k, mortgage at about $200k) and we will end up selling off half of what MIGHT be our entire retirement!
The reason I am considering it however, is that I am wondering if we could (despite no income at the moment and therefore no option for traditional financing) leverage the proceeds into something bigger/more units, that would be better for us given our circumstances??

I have heard SO MANY TIMES that everyone who sells regrets it later and I feel like I am trying to get back in the game SO late in life in terms of the number of years left before we will want/need to have a retirement in place....and just not sure I am even thinking about this right or completely.  

Any insight or respectful advice would be much appreciated and welcomed.  Thanks so much in advance.