I'm so sorry you are dealing with all of that

The hospice group may have a list of local resources for you.

Your medical provider may have a list of local caregiver support information as well- resources they don't provide, but can point you to.

If there's an agency where you live, something along the lines of "the council on aging", they might also offer information.

Don't feel badly if you prioritize yourself and H, and end up putting down strong boundaries with extended family. If there's ever a time when you are entitled to do that, it's now. Shame on them for not having it in them to be more supportive of the situation. Unfortunately, it's not uncommon for family members to behave that way.