Quick Background:

• Divorced approx 18 months. Amicably.
• Mortgage on marital home is still in my name.
• she is on title/deed.
• we decided to leave mortgage in my name because of the extremely low interest rate from when we refi’d a few years ago.
• Bank refused to allow her to assume mortgage. And she wouldn’t be able to afford monthly payment if we did cash out refi.
• there is very detailed language in divorce decree that she is responsible for all debt on house from divorce date forward.
• we also agreed that based on current market conditions my portion of the equity was $125k.
• remaining mortgage is approx $285k
• 3 independent appraisals put home value between $515-$540k
• I have a promissory note that guarantees me $125k NET, regardless of sale price, if/when she sells. If the full $125k can’t be paid in full at time of sale, she has to repay me the balance over 10 years.

So now the situation:

I have found a home I’ve put on offer on. Contract price $420k. I have approx $80k cash for down payment.

But with my debt to income, and desired monthly mortgage payment, I need to put down $120k. So I’m $40k short.

Is there anyway to collateralize the equity/promissory note to get the additional cash needed for the down payment?