There are several threads here on breeding loans and some people swear by them - not me. They are one of the most frequent transaction for problems, because they happen over a long period of time and people's memory of the original agreement gets fuzzy after a while.
I know it has been said many times in this thread, but to minimize the damage, breeding loans need to have very detailed contracts covering every contingency. For example, if one of the snakes get sick, who pays the vet bills? If a loaned snake dies, is there compensation for the loss? If a loaned snake produces something really odd, who gets it? If the person who has possession of the snakes moves, how involved is the loaner in making sure the snakes are transferred properly or are even transferred to a new location at all? If the loanee moves, who pays shipping for the snakes to be returned. How do you split the clutches? The list goes on and on and that is the reason that I don't do them. It is very difficult to account for every contingency.
If I were in your shoes, I'd just get my snakes back. Once that is done, I'd remind the other party that you are owed snakes if they are produced and leave it at that. I would not expect to get anything out of the deal. Chalk it up as a very hard learning experience.