In the past months he has worsened in temperament and action.

As long as the bulge isn’t too bad (or worsening with the stars/bolts).

Basically it'd be 1300*.75 - 1400, so this particular deal would actually worsen your DTI.

That significantly worsened cash flow.  

I don't think it will cashflow at 43% of the mortgage payment, so wouldn't the loan add more to the debt, than the rent will ad to my income, hence worsening my ratio?

Had you extended yourself on something other than the buy and hold portfolio that got you into trouble.I would think that after 17 years, you'd have had so much equity and cash flow on some of your early properties that even during the crunch you'd have been able to weather that storm better than say a flipper who might have been stuck with 4 or 5 houses that they couldn't sell and were too far underwater to sell as the crash worsened.

I fear that this issue will only worsen once we are no longer living under the same roof.I am hoping to get some advice on how to proceed from here.

That will worsen as the market continues to slow.

The economic situation is starting to worsen and rents are at an all time high in many markets.

Be careful of whatever deductions/renovations you claim on your SchE as that will go against you and worsen your dti.Other strategies that come to mind are basically higher to much higher risk and/or may only work in certain situations.