Should I sign a prenup?

Yes.

Although there is no single, standard answer for all situations, all soon-to-be-married couples should seriously consider negotiating a pre-nuptial agreement. A solid pre-nup, ideally negotiated with the assistance of lawyers, crystallizes your understanding and expectations in the unfortunate event you and your new spouse later divorce.
Since the pre-nup is a legal contract that covers how you want to divide and allocate your assets and liabilities, it can ensure these items remain in the right hands. For example, if one of you has significantly more income, personal or business assets, or investments than the other – or conversely, if one of you has a higher level of debt – then a pre-nup can ensure that the post-split allocation of those items is acceptable to you both. This way, you and your intended spouse can take control and determine exactly what happens if you decide to divorce, rather than leaving that job to the courts.