Protecting my startup from the current FT employer.

Background: Intentionally vague

I solved a problem at the company I work for that plagues the industry we're in but developed an even better solution for it outside of work that I want to sell to other companies (maybe even my current employer).

I developed a concept for solving a particular problem while working at a F500 corporation. It was implemented by me through a series of Excel formulas and VBA scripts.

I then, on my own time, hardware, and space, created a piece of software that solves the problem faster, simpler, and with several new features. It is not excel based, though it does output to excel.

I now want to start pitching companies this software but want to make sure there is no chance I am breaking the law, risking a lawsuit from my employer, etc.

I have zero knowledge about IP.

Questions

• What's the best way for me to go about doing this and remain legally sound?
• I should schedule time with an attorney to look over my employment paperwork and get their opinion, but what kind of lawyer should I be looking for and what can I expect to pay?
• Should I tell my current employer about this? I need to keep my job to survive but also don't want them thinking they have ownership of my creation.