Tape is unfortunately uneconomical for regular people due to the drives costing so much, unless you get a used, older generation one.
How many GB’s do you mean? Maybe try some optical discs, BD-R at 25GB maybe.
Otherwise just rent some online storage. Hetzner Storage Box is cheap and Storage Share is only slightly less cheap, and has lots of sharing features (it’s really NextCloud).
I think the stuff you’re describing is outside the range where we internet randos can give any concrete help. You’re doing the right thing in seeing professionals who have actual training in dealing with this stuff. I can only offer sympathy and best wishes.
I find if I get agitated about something, I can often calm myself down with deep breathing. But I’m sure my experiences are less intense than yours to begin with, so I have no idea whether the same methods would work for you.