I have fixed similar things in leather before by fashioning a small leather patch larger than the tear and working into the tear, then carefully get Gorilla glue under the tear to adhere the patch. Dampen the patch before so the one-part epoxy will react and cause a strong bond. This method will hold the tear closed but will not make it disappear. It will stop it from expanding. I know they make auto leather repair kits, but they have never given me satisfactory results in making the repair invisible. You have to match color first, which of course changes as it cures. Then you have to spread it over the split and then apply a tool that is supposed to give it a leather look. Well, all you have done is create a larger mess than you started with and it will not last long.