Phew, I'm glad your pup is OK. What I would do is kindly point out that the vet bills will be expensive, and that perhaps he should pay at least half ( all if you are a good haggler ) of the bills. If he decilnes reimbursement, I would mention that certain laws say that uncontrolled aggresive dogs should be put down, or trained, or at least ( the owners ) be responsible. Sometimes laws require that the attacker's owner pay for damages. If he continually refuses, point out that you *might go to animal control. If this doesn't change his mind, go to animal control. Ask them for further sueing/court matters, ( as I do not know what area you reside in )

Wishing you the best.

Happy healing.

P.S. In my opinion, small dogs ( and cats ) sometimes trigger the prey drive. My greyhound X has gone after Toy breeds (and cats )with that *look in her eyes.