I came across one of these loan agreements online somewhere a few months ago, can't recall where I found it but it was clear in reading the loan agreement there was no language referencing the loan actually encumbering real property, it was just an unsecured loan. 

I have 2 options:- finance the construction pre-selling the apt, and take my profits (expected to be around 700K pre-tax); or- finance the construction with a 6-7%/year loan (collateral = my house), keep the 10 units, and once the building is completed in 24 months, rent them for circa 180K/ year gross.

If her goal is to provide some of the proceeds to her ex in good faith, she can simply sell the property, have a tax professional estimate the taxable gains.

If you sell for $460k and it costs you say $30k to sell, you net $430k.

If you decide to sell I would sell it vacant.

Here are 5 lessons I learned from selling my laundromat last year that can help you as a prospective business buyer.Lesson 1️⃣ - Listing sites can be a legitimate way to buy and sell a business.I will often hear people say that they’re not even going on listing sites because “they only have bottom of the barrel listings,” but this has not been my personal experience.

Assuming your property is in Utah (like your profile indicates), here's the state law from a basic internet search:In Utah, a tenant who abandons a rental property without notice is liable for the lesser of the following: The rent remaining on the leaseThe rent plus the difference between the fair rental value and the agreed-upon rentThe cost to restore the property to its original conditionThe landlord can also remove the tenant's belongings and sell them if the tenant doesn't claim them within a reasonable time.

I'm willing to sell the other at cost. 

If it sucks for you, you can sell and be further ahead than you already are today.

sell it to the tenants