As already stated you have fulfilled your responsibilities, Take one or two space heaters and do not give a rent rebate...sets a bad precedent and not required under the circumstances.

Meaning they fulfill the lease and give proper notice before moving.

From the very start of the transaction he was very demanding and I fulfilled most of his requirement.

They just do it because it fulfills them at a different level. 

They sent me cabinets that were in different boxes, different construction, door sizes were off a half an inch, a pinstripe was a different color, they couldn't fulfill the order with the cabinets I ordered so they gave me different cabinets and said that they would work?

Last year my brother and I fulfilled a lifelong goal of going into business together as Landlords.

She can quit all day long but she has to fulfill the contract otherwise she’s in breach.

And even if you have one, wouldn't you want more transparency with who the borrower is, their track record, property LTV, title and whether they fulfilled certain milestones before making another draw of capital?

That might motivate them to fulfill a binding contract to sell to you.I can't imagine signing a purchase contract (esp if it was for a primary residence) in which the seller could simply cancel for a better offer. 

If you have fulfilled your side of the agreement, he can't evict you.