Although you haven't indicated what the family lawyers have said about your case, and why they say they can't help you, from your description, it appears there are a number of legal and practical issues you are facing which may make your case not worthwhile pursusing:
1. it appears your Ex has only modest assets to claim against, so even if you successfully sue him, he may not have the money to pay you;
2. If the total amount in issue is just the 30K debt and particularly if only some of it can actually be proven to be his improper use of the funds, then it may not be worth pursuing if the legal and evidentiary issues are going to be very expensive to properly investigate and present to the court.
3. Despite the age of your relationship, it appears your matter is not governed by the Family Law Act, which only applies to married couples, or those in de facto relationships for 2 years (or where there is a child of the relationship). This means, the law which relates to your situation is somewhat more complicated and may prove expensive to litigate (perhaps many tens of thousands of dollars).
If you wish to proceed you will have to continue hunting to find a lawyer willing to act on your case as a claim of this is not something that should be attempted without proper legal representation. I suggest you check with your state's law society as they can refer you to a suitable lawyer in your area.
I appreciate this is not the answer you were likely hoping for, but it does reflect the reality of your situation and I trust my answer at least assists your understanding as to the obstacles you face.