If that's true and you aren't actually violating an NDA or Covenant Not to Compete and your independent development was done neither on compay time nore on compay equipment/software, you could just pretend that they don't exist and ignore them.
In addition to what Jeff has already said, any communication in work duration / work environments by emails (official) or work phone is also property of your employer thus (if applicable) company has right to claim on the outcome (or revenue generated) of it. In fact if we go by definition, any idea expressed in written or verbally is company property.
It would be very complicated if your employer takes special interest in your own work. He would like to in-cash this opportunity. You must consult a lawyer if stress increases.