patching cable but cannot use heatshrink tubing

I was planning to protect a peeled spot in my cable by sliding a heatshrink tube over the spot and heating it. However the cable has a 90° bend at the end where it plugs into the computer and this is preventing me from sliding the tube in (on the other end there’s a big square adapter so also impossible on that side). Any ideas on alternative ways to patch the spot?

The biggest tube I have is 1/2” which shrinks to 4mm. I think a bigger tube is not the answer as it wouldn’t shrink enough right?