My fiancé's secret loan debt was revealed

So girls, we were thinking about getting married next year and had been planning everything together, but I accidentally saw a bank message on his phone last night. It turns out he's really racked up a debt of sixty thousand lira and never told me about it. When I asked him, he brushed it off as something old or whatever, but honestly, I don't feel at ease at all; my trust has been seriously shaken. Do you think this situation will cause big problems for me once we're married, or am I overreacting? Give me some advice.