sell or hold duplex?

[Matt Williams]

Hi, new to BP.  So....I have a duplex in a crappy neighborhood. for months, a company out of the metroplex has been offering to buy it. diamond holdings and aquistions. So we agreed to $170k. It is only worth $120k, so I thought why not?
However, now I am having second thoughts. It is all paid off, and I am making $1400/mo cash flow. I depend on that cash flow as my income every month.
Cash flow is my primary goal right now. I had a converstion with a mentor a while back, and He thought I should sell one of my rentals (I have two, both fully paid off) and then pursue passive investing. Which is why I decided to talk to Diamond about selling.
I have signed the contract with diamond.
So after long term cap gains tax eats about $20k. I am left with $150. $20k for the sophisticated investor class, and then only two passive deals at $50k each . Then, I have to wait years on any income, right? I am not convinced this is a good path.
Your thoughts?