marriage and pre-existing debt

My boyfriend wants to get married. I'm worried he has great credit, but my credit sucks. Would he become liable for my bills if we marry? And if so, is there a way with a pre-nupt that I can make sure they can't touch his stuff? My debt is a result of taking care of my brother after my parents died. He older and mentally retarted, it took about 2 years to get him benefits - Is this your question? Add additional information