I have been in a situation like that, when I worked for a company that had me managing 12 to 30 clients directly. There is a standard solution to this problem: a ticket / issue system. If clients won't use that, and you need to keep them, then hire someone to transcribe their issues into the system, and increase your prices to cover it.
The clients might find that they prefer interacting with a more business/people oriented person, rather than a stressed out INTP. That person could also help you schedule and estimate work, without needing to have programming skills themselves; another source of stress mitigated. In theory, recovering your full productivity would lead to a net increase in the value of your services, despite the expense of this new person on staff.
The clients might find that they prefer interacting with a more business/people oriented person, rather than a stressed out INTP. That person could also help you schedule and estimate work, without needing to have programming skills themselves; another source of stress mitigated. In theory, recovering your full productivity would lead to a net increase in the value of your services, despite the expense of this new person on staff.