Ask HN: How to avoid conflict of interest?

Hello everyone, for the past couple of days I've been working on a very small personal web project. I am currently employed at a small newspaper. I am at a point where I feel comfortable making my project available to the public.

I highly doubt I will bankrupt my employer, but I would be providing free advertising to a targeted group of local businesses. Now I am having second thoughts about making my project live. I would hate to lose my job over this.

Has anyone been in a similar situation? How did you deal with conflict of interest?