There are a number of issues that need to be looked at.
1. Does your employment Agreement cover such a situation?
2. Have you been developing IP in the same area that you have been hired to work on for your present employer; and
3. Have you been using your employer's facilities and equipment o work on your innovation, and
4. Have you been working on your IP/Venture on company time.
I strongly suggest that you consult with an experienced Intellectual Property attorney who can look at your materials and counsel you confidentially. This is important, since you don't want to face a claim or lawsuit from your employer when you launch your new business.