Hello, guiltier65. Perhaps of benefit:

What If You Don?t Like Your Therapist? | Psych Central
Therapists Spill: How I Set & Sustain Boundaries | Psych Central
The Steep Costs of Caregiving | Aging Well
https://www.caring.com/caregiver-wellness
4 Secrets for Setting Rock-Solid Boundaries | World of Psychology
https://www.medicare.gov/contacts/#findsomeone&stateCode=KS|Kansas
https://www.caring.com/questions/med...mily-caregiver
https://www.caring.com/articles/paym...mily-caregiver

Are there siblings who could be helping you help your parents? If so, why aren't they?

Take care of yourself.