The debt predated the marriage. It is also not the same as a standard debt. Repayment is based on income, not on regular repayment over a fixed term. It reduces his net income. I think it should be squarely seen as his debt. I believe a court would concur.
Yours would appear to be a fairly short marriage. If there are no children, the approach would be that you each take out what you put in and split profits and joint debts equally between you.
If you are representing yourself and need some support, it may be worth talking to the helpline about some of our fixed price services for LIPs.