It seems like the best thing for you and the company you work for is for you to let them know and give them the option of letting you split time at both compani

It seems like the best thing for you and the company you work for is for you to let them know and give them the option of letting you split time at both companies or lose you completely. You will definitely want to talk to a lawyer who can make sure you have your rear end covered in case your employer wants to get a lawsuit going against you, and get the employer to sign an agreement that you are free to your side venture without fear of getting sued as long as you keep your work separate from theirs. If they think they need you, it would give them the opportunity to keep you around for a while. If they don't, you don't have to feel like you left them high and dry. But DEFINITELY make sure that you have your ass covered legally if they decide to have you keep working with them!!!