Oh dear. I’m sure he feels badly.
When I went off to college, my saddle stayed behind at home with the girl who was free leasing my horse. Not sure how it happened (she never owned up to it), but the cantle got a large gash in it, actually tearing the leather from the lip of the cantle downwards about an inch or so down the back of the cantle. I was furious. My beloved Barnsby was ruined. I cried - alot!
So I totally get your frustration.
Luckily my father had friends at Gucci (my dad worked in upper management at Bally of Switzerland). So my dad contacted the leather workers there, and took my saddle into Gucci in NYC and they fixed it by adding (glued/cemented) all new leather OVER the whole backend of the saddle -, about 3" into the seat, over the cantle, and to the edge of the saddle. Looked great. They did an awesome job matching the leather. Still looks great - even though the repair was done in 1982. 
So, take your saddle to a leather repair shop (if you don’t have a good saddle maker/repair place in your area) - just make sure its a good one. My guess is they can repair it. Will it look exactly the same? No - but your rear is going to be covering most of the repair up - so who will know but you?
I’ll try to remember to take a photo of my repaired saddle tomorrow and post.