If a woman owns everything when a man marries her, is he entitled to anything when they divorce?

No what was hers coming into the marriage remains hers. You might have gained a small amount of interest if community funds were used to pay on loans of her assets. Like if she has a mortgage on her house with a payment of $800 a month, but it reduces her principle only $100 each month.? As the mortgage was paid with community money, you acquired $50 value in her house for each month you were married.? But if you have pension and you had $100 withdrawn to pay into your pension.? She acquired $50 a month interest in your pension. It is a wash.

You can't scam an honest man, so it sounds like there may be more to it than being set up. Regardless, you are entitled to one-half the community property. If she kept her assets separate from you, she probably has a good case that you can't touch them. On the other hand, to the extent that community funds were used to enhance or pay for her property, you may be entitled to one-half of that amount. I suggest you talk with a local attorney and see if there is anything for you. Oh, and if you signed a pre-nup and had the opportunity to run it by an attorney, then you are really out of luck.

In Utah, generally no.separate property owned prior to the marriage remained separate property in a divorce unless the spouse seeking a share of that property can prove to the court that the separate property was either made marital property by choice of the owner or that the separate property was "co-mingled" with marital property.

Marital assets are usually property accumulated during the course of the marriage. There are some exceptions so check with a local attorney.