Can the photographer legally use my photos if we do not have a contract?

I do not understand all the details here. Let me see if I have this correct. Were you posing for nude photos that he would use and doing that as a form of compensation to him? And in exchange, he was going to work as a photographer for you for your website? In other words, was he exchanging being able to exploit photos of you as compensation for working for you? But that deal was oral and not in writing? The photographer may own the copyright to the photos, but you own the right to your image, which cannot be used without your permission. Hire a lawyer to send him a letter and have him delete all copies of the photos and never use them. Then keep your eye out to see if he is showing the photos. If anyone is considering posing for nude or compromising photos or videos, they should have a lawyer involved. Getting such photos or videos can harm or outright destroy your career or jobs for many years. It can change your whole life, and usually for the worse.

In many jurisdictions verbal agreements for products valued at under $500 will be valid. The issue may turn on whether both sides received the agreed on product/service. It seems that you have a good argument that by failing to deliver the quality photographs you bartered for, the photographer may have breached the agreement.