Personally, this sounds like the black dog of depression to me. Modifying your environment and work position may or may not help. My advise is to maybe try some professional counseling first so OP can get some help in working it out.
The table's a mess. We're having a hard time figure out how to rearrange it. So, the "stranger" tells you to tip it all on the floor, you, not sure what happens when you do it, does it, and after a few moments, whatever we really need back on the table, we will pick it up, despite what the "stranger" says. We end up with what we really want, and everything else on the floor.
Sometimes family is really hurting ourselves, and it can be a wise choice to screw them and leave. A close relative of mine killed himself after years of emotional abuse from his mother. That's stuff that's happened to me before, and if, to survive, I have to leave whoever it is to sink or swim, then screw them. My survival and sanity is of prime importance. Sometimes, taking care of family is a luxury we can't afford.
Most importantly: you are the most precious person to yourself, love this guy.
Try maybe to realise that your existencial fears come from all past failures and dangerous situations, your limbic system just attacks you with the scarry visions, because this is what it evolved for: "see the tiger, recognize threat, run!" You could then do it like Zen buddhists: "I see the feeling coming, I look at it, I observe it, I know where it comes from, and I gracefully let it go".