My Mom in law requires constant care in hygeine, dressing, transfers, medication, feeding, appts, etc.
My dad-in-law needs help with medication, feeding, driving to appts. etc. He is blind and nearly deaf, MIL has parkinsons and congestisve heartfailure and can't walkor transferor bathe, toilet, eat, everything.
If you are truly taking on all this care by yourself, you will soon be the one needing care. (do you have cna training...transfers and lifting can wreck your back.)
Sit down with hub and any inlaws in the area and explain that you need help. If there is no other family in the area, hire a caregiver to do the things that are most difficult for you. Or have them sit with your in-laws while you take a well deserved break.
There is no "set" amount of time for respite. You are in control....take the time you need, whenever you need it.
Good luck and take care of yourself.
Lilli