Create a Web Application in Ruby

I require a web application with the following features: It needs to be an online word processor which allows secure access to individuals who are given a certain link. The best way to explain is through an example: Person A has a document, and want's person B to make some changes to the document. Person A writes a document using this basic web application, then sends a unique link to person B so that they can access and make changes to the document. Any changes that person B makes will be highlighted to person A. Each specific version of the document must be saved on our servers. This process must be secure. I am not 100% set on Ruby if you believe there are better options, however I will need to be convinced of why. Please message me with your questions, and your (very rough) estimated budget. Thanks