Hi Frank,
Sounds like you are going through some difficult times, it is frustrating when things are beyond your control.
Do you live in a city or in the country?
I had an older rural property about 10 years ago that had frequent water supply and septic system problems. The solution was simple for us, use the existing outhouse that was onsite until the problem was fixed. I grew-up around bush camps so it did not bother me much but my wife hated it, that house had so many problems it is a wonder we did not get divorced over it.
When we sold the house the buyer did not want the old outhouse (it must be 50 years old but very solid) so I took it to my hunt camp where we still use it.
I do not know if your Municipality would let you install an outhouse, but a rental Pot-a-potty may be a viable option for the short term.
Your homeowners insurance may pay for the rental fee and repair if the sewer backed-up into your house, check your policy?
Hope things turn around for you,
Mike