So, let me give you some actual numbers. You need to adjust them to fit your situation, but this will show you why I think this is too thin.
$112,000 purchase price
$3,360 purchase closing costs
$6,750 hard money points (5 points)
$10,125 hard money interest (15%, 6 months)
$4,000 holding costs (utilities, taxes, insurance, maintenance)
$135,235 total cash needed
$135,000 hard money loan amount
$140,000 selling price
$11,200 closing costs
$128,800 net after costs
-$6,200 net after paying off loan
Now if you have your own money, you can save almost $17,000 in hard money costs. If you get conventional financing, say 1 point and 7%, you save $11,000 in money costs. If you FSBO it successfully, you'll know 3%, $4,200 off the sales closing costs. Lot of if's there.
Now, you mentioned doing a lease option. Not sure that would work with your weak seller, but a creative technique like subject to where you assume her loan might. You'll have to pay to get caught up and continue to make the payments.
Jon