Dog Decision-help

So, ok...

My dog had a seizure about 2 wks. ago & I took her to the Vet last Friday. They ran some blood work & found out that the problem is something w/her liver. She has a blood vessel that isn't passing thru the liver, so some of the bad stuff is gettin into her system that the liver should be filtering out.

I can have this surgically fixed for like $800-$1,500 ( ) Or, we can change up her diet & hope that the problem doesn't worsen. The Dr. said that statistically though, they worsen & eventually die, but he has 1 poodle w/this problem that changed its diet & is fine now. But that's ONE case. Or, I can have her put down. She's only 1 yr. & 3 months old.

Thing is: when I got this dog, he leg was out of socket, so I spent like $300 to get that fixed, then I had her spayed (or whatever) which was like $50, plus the pet deposit at my apt. $300...

I've put so much money into her already...what do I do now???? I love her to death, so I don't think that putting her down is something I could do... I don't know, I NEED