First off here's a huge hug for you
I was a Activity Director in long term care and rehab. facility, over 15 years in the field, I worked in several with different facilities with varying degrees and practices, and very closely with therapy, social and mental health services, and nursing. In activities most residents would relax and say or do things that they would not around the nurses or therapist, so sometimes I would get a different outlook on the resident.
Did they do a care plan with you before discharge? did they do a home visit so that they could evaluate your home and match it to what he is or is not capable of doing, before sending you home? Did they offer home health care? Did they have him show you what he can or can not do? Did they offer any guidance in helping him transfer? is your bathroom set up with grab bars or/and a raised toilet seat? Some.. really most of these things should have been addressed before you took him home, in all the facilities that I have worked in was common practice.
While in therapy was he on Medicare? They will only keep him the allotted time, It was 100 day or so with each illness, you need to check to see how long he was there, once the days are reached, then they release him, It's not the fault of the therapist, unfortunately its about the Medicare dollars. Normally before you can tap into Medicare again there has to be a hospital stay. Please know that I not been in the field in about 8 years and the Medicare laws change like the wind, so do some research.
Do you have some sort of supplemental? Medicaid? If not you need to start the process right away. Any VA benefits?
Call your insurance company, keep going up till you get someone to listen.
Does he have a case worker? if so contact them right away and keep contacting them to see where they are and what if any progress they are making, but please be kind to them they work hard and have lots of other clients to help.
Contact his Doctor, and be frank with him or her. While this may sound cold or mean, you need to tell them you can not care for him in this state.
Also when was the last time his med's where evaluated, some times they need to be changed to some degree, more or less or a different brand.
Call the facility and ask to speak with the Administrator, and the Social services person or case worker.
Join a group with other caregivers, this will give you an outlet and no-one will judge you.
Contact the local Diabetes Association they might have some avenues for you.
Contact your church and talk with the pastor, he may have some suggestions for you.
Call the department of Elder Affair's or Ombudsmen's - the are a great source.
Ask for help, adult children, family, church members, any organization that he might have belonged to Moose, VFW etc.. even if it just for a hour for you to go to the grocery store. That time away will fortify you.
The hard thing here,
is what can he really do for himself and
what he really can not do for himself and
what he is or is not choosing to do for himself.
While in the facility some residents get use to someone being there all the time so they have 24 hours service, activities, meals prepared and delivered to them, help with bathing and bathroom visit, special treatment and someone fussing over them (everyone likes to feel special) Once at home that all stops to some degree and some resent having to do for themselves, and act out. Some even blame or try punish the family or spouse for what think they are not doing for them. I am not saying this is the issue, just offering up some insight at some other cases that I have worked with.
For yourself and your sanity,
you have to realize that you have to take care of yourself, and that his health issues are not your doing.
Another hug

and pixie dust

coming your way.