Nereo,
Here are a few other things to consider. First, there are transaction costs that would reduce your net equity if you were to sell. If you were to sell this place and replace it with something "better", it would have to be enough better to cover both the sale and purchase transaction costs (think realtor commission, title insurance, appraisal, inspection, transfer tax, new loan costs, escrow/attorney fees, etc). Next, you know this property and it's maintenance history. If you were to find a replacement property that was "better", even after transaction fees, you would be dependent on the inspector's identify any deferred maintenance. Lastly, and some may argue with this one shouldn't be part of the equation, assuming you're in the US, consider what the IRS allows you to take in depreciation on the building. You may actually be positive on an annual basis right now.
+1 on considering the opportunity costs. Of course, selling it eliminates the option to move back. Holding it for a small monthly outlay keeps that option open for as long as you want. How valuable is that option?
Let us know how things progress.