How do I say no to someone who has asked me for a copy of my lesson plan that I have spent hours on?

I am currently student teaching and created a lesson that incorporates technology and art. The person who has asked me for the lesson is a fellow clmate who has in the past let me down. We are told that it is professional to share your resources with your colleagues, but at the same time I have a lesson plan, hand out (with many hand drawn examples), rubric, videos, power points, guided worksheets, vocabulary bingo games, etc. that I spent hours on. This person has offered an exchange lesson (but it is on a topic I do not care for), so how do I say no?